IF you have already progressed through all your sexual development cycles, you likely have a condition known as "micro-penis" - where a normal, healthy, functioning penis remains at a non-adolescent size.
The best time to treat this condition is when you are a toddler - if it's identified in time. Treatments can add up to 2 inches to your size. That would place it in a normal size range.
There are new treatments that work on post-adolescent men. The sooner you start that treatment though, the better. So go right away to your doctor - get a referral to a specialist and start working with him/her right away. It's not an unknown condition - though some general physicians are not as familiar with it. So do mention that you need a referral for "micro-penis condition". Your doctor can always look that up and find the appropriate specialist.
Meanwhile, you may want to look online and find a micro-penis men's support group (other men with the same condition), as this problem can cause you a lot of anxiety. Do keep in mind that some support groups feature men who either do not respond to treatment or were not diagnosed in time for treatment - so they will have different perspectives on issues associated with it.
....and from a completely personal perspective - stay away from porn. It will skew your ideas of healthy sexual relationships in a really negative way - especially as you work with this particular issue. A partner who loves you, will love YOU - not your penis. It's just a part of your body - and plays whatever importance in sex that you allow for. Healthy sex lives are built on trust, on learning each other's bodies and pleasure centers - not on the unrealistic sizes or fantasies played out with porn.
Hi Garlog - I'm not a man - so I wouldn't know about excersizes.
Micro-penis is hormone related though - not a simple matter of a normally smaller penis. So it is really, really important to get to a doctor and begin whatever hormone therapy you can - as soon as possible.
The younger you are when you start the treatment - the better the response. Also - just to be sure - check your penis when erect and see if it has a normal circumferance for an adult penis. (ie: is it very small like a child - or relatively large around and just short). If the circumference is normal, a doctor may direct you to other treatments immediately. If the circumference is not - then hormone therapy is usually the first line of treatment (at least from what I understand of the condition).
As a woman - I'll be honest with you - micro-penis can present some issues in relationships - if you're running after multiple partners or trying to be a playboy. That's not going to work.
It may even make you a better man. You will need to learn different ways to pleasure yourself and your partner. You can become a fantastic lover with a willing partner and keep that person satisfied, happy and build a great relationship - even without treatment. Having treatment though can improve the condition and increase your own self confidence.
A loving partner won't care about the size of your penis if you care enough to learn how to be a great lover, a great man and a great person. ...that's the plain, honest truth. ...but you will care - and that's why I would suggest going immediately for treatments - for whatever is available.