We're all, probably, quite familiar with the stereotypes. "People with Asperger's are typically male, socially awkward, work in IT, are great at math, and flap their hands." Yes, the other stereotypes are just there for illustrative purposes, and they can be just as "off" for individual Aspies as the idea that Aspies are usually male. It's the gender thing we'll focus on here, however, and it's quite a prevalent idea. You can easily find scientific studies to back the idea that males are simply autistic in higher numbers than women .
Females on the autism spectrum are, some people are quite adamant, more likely to express their autism in socially acceptable and less noticeable ways, as well as to gain the skills that allow them to pass for neurotypical. If you're an Aspie woman, that might mean that you've flown under the radar for most of your life, personally being more aware of how different you are to most people you encounter than those other people ever were. Even if you're considered slightly eccentric.
Hanging around the "Autism-sphere" on the web, I've found out — anecdotally, not scientifically, of course — that it's not at all unusual for autistic women, even those with the "level 2 autism" that is considered to be moderate rather than mild, to go undiagnosed until much later in life. These women were always autistic, of course; it's just that nobody picked up on it. If this is your story, too, it might well be you, yourself, who finally uncovers the right diagnosis as you start exploring the signs of Asperger's in adults. You're then in the situation where you might feel the need to approach healthcare providers with the message — I think I'm autistic, can you diagnose me?
What Does Science Have To Say About The Idea That Women With Asperger's Are Different?
Quite a lot, as it happens — though perhaps not enough, which we'll get to in a bit.
The Empathy Quotient, a 60-item questionnaire, is one of the measures used to assess whether people are on the autistic spectrum. Featured statements, to which subjects are supposed to answer with various degrees of agreement or disagreement, include "I really enjoy caring for other people", "I prefer animals to humans", and "I can sense if I am intruding, even if the other person doesn't tell me". One study found that women score higher on the EQ than men. This is true in the neurotypical population as well as in the autism spectrum and Asperger population. 
Systemizing, which is often seen as the opposite of empathy, refers to the ability or tendency to analyze systems rather than people and is often seen as one of the key signs of autism. This can include machines (like cars or sewing machines) as well as political and social systems, plants, computer operating systems, or mathematics, for instance. How do you think women on the autistic spectrum score on this measure? If you think autistic (and other) men are more likely to engage in systemizing than men, you'd be right. 
Women with autism score slightly, but still significantly, higher on a test where they're asked to decide how a person is feeling based on looking at their eyes as well . Something similar can be said for a test where people are asked to infer someone's state of mind from their voice, though the study included only a few women in this case .
While those who first described various variants of autism, namely Leo Kanner and Hans Asperger (after whom Asperger syndrome is named) both noted sex differences, Kanner saying the condition he described occurred in boys four times more often than in boys  and Asperger exclusively describing boys , they may simply not have "looked in all the right places". Today, we sure do know that girls and women can be on the autistic spectrum too, after all.
Asperger Syndrome In Women: What If Science Doesn 't Have All The Answers (Yet)?
Tania Marshall, an Autism Studies PhD student, came up with a list of characteristics she's observed in the female Aspies she has worked with. While this doesn't constitute a peer-reviewed journal, you'll certainly be interested if you're a woman and currently wondering whether you could be on the autism spectrum.
Ms Marshall describes women with Asperger's as generally being rather intelligent but often suffering from learning disabilities such as dyscalculia or dyslexia, having good long-term memory but poor short-term memory, and displaying rigid, black and white, thinking. They may, she says, have a history of dropping out and re-enrolling in educational programs. These traits are related to executive dysfunction. Nonetheless, adult women with autism are often successful in artistic professions, where they may be experts in their fields. While they are hard-working and try to avoid making mistakes, they may find working with many other people overwhelming, and take sick days for this reason. When they've had enough, they may suddenly "burn bridges", by walking out of work with no notice for instance.
Women on the autistic spectrum also, she says, prefer one-on-one social situations to group situations and need a lot of solitude. They may have trouble with friendships, including because they might have alexithymia, an inability to express emotions well. They may be clumsy, get overwhelmed, and find it hard to deal with noise and other sensory issues. Like most autists, they are likely to have a "special interest" or several, within which they're likely to take on leadership positions. [8 — and since this isn't a scientific journal, you'll find the reference in the links box at the bottom of the article. I'll do the same for the not entirely scientific but still incredibly useful resources that follow.]
Samantha Craft, a woman diagnosed as being on the autism spectrum, has her own, overlapping, ideas. Since placing her full list of autism symptoms in women here would make things rather too long, I'll select a few:
- Deep, analytic, thinker who doesn't simplify things.
- Naive, honest, finds it hard to lie.
- Experiences feelings of isolation.
- Is easily taken advantage of.
- Escapes the "real world" through action, philosophy, creating patterns, or fantasy.
- Is a master at imitating others.
- Usually makes friends with older and younger people, and has had troubles in the field of friendship.
- Poor muscle tone, clumsy, may have obsessive-compulsive tendencies. 
As an undiagnosed woman on the spectrum, you may be acutely aware that you are very different to most people you encounter in daily life — and as an adult undiagnosed woman on the spectrum, you'll have had years to learn to imitate others in order to appear normal, though this may involve a great effort on your part. 
If you poke around the web, you'll also stumble on the idea that female children with autism are more likely to express themselves in socially acceptable, more "normal-looking" manners. Common ideas are, for instance, that autistic girls often like to play with dolls, but prefer to line them up and dress and undress them. To a parent or teacher, it may wrongly look like the child is engaged in pretend play. Likewise, such a child's special interest may fall within a "stereotypically female" sphere, such as fashion, unicorns, or the movie Frozen.
It's not hard to find female autists who reject this notion as being just as stereotypical as the idea that all male autists work in IT, either. At the end of the day, autism, as a neurological difference, is expressed in ways that are as unique as autistic individuals themselves. Autists share many underlying similiarities, of course, but those are expressed very differently in different people.
Does This Sound All Too Familiar And Are You Now Wondering If You Could Be On The Autistic Spectrum?
We'd advise you to keep reading. Do all the autism screening tests you can find online, like the Autism Quotient and the Rdos Aspie test. Talk to already diagnosed adult Aspies and other autists while exploring the autism spectrum later in life — scientific research is useful, but really fails to cover it all when it comes to women on the spectrum.
When you're ready, should you feel the need, approach your family doctor or an autism specialist directly, and pursue a formal diagnosis.  Should you want to do this, however, you may like to specifically look out for someone who has experience with diagnosing adult women with autism. Bring as many examples of the reasons you believe you may be an adult on the autism spectrum along, and if you like, even ask your parents or an older relative to write down what you were like as a child. All these things will help during the evaluation.