But when I'm at home or something, I'm really quiet, and shy-ish.
And i hate meeting new people.
Does that mean I'm bipolar?
Reading what you wrote- I'd say you're more than likely a normal teenager!
We all act differently in different situations, ie; when at home or with friends. Personality is like air- it's mutable; in otherwords, it can change. Yet just as nothing on earth can change it's original atomic structure- our personality has core characteristics (these are usually rooted in our moral behaviour & beliefs).
However, this does not mean you are bi-polar. Having manic depression (otherwise known as bi-polar disorder) is very different from changing your personality to suit the circumstances. BP disorder sufferers have a lot of severe varying changes to their personality and rarely look for help or recognise that their personality is changing so drastically. Also- it's not usually diagnosed until adulthood and more likely, after quite a few suicide attempts, high credit card bills, dangerous & semi-psychotic behaviour.
One thing I did pick up in your post, though- you said you hate meeting new people. This is confidence problem.
I'm guessing you are in the 12-15 years old age range? If so, you are going through your 'Identity Formation' years. This means you are trying to identify your existing personality with those of people around you. When you can't identify anyone like you, you become confussed & can't seem to fit yourself in any social 'boxes' (stereotypical groups). This leads to a loss in confidence, a tendency to 'do crazy things' in order to fit in with a group & a fear of meeting new social groups because you fear you won't be accepted by them.
I would suggest you speak to someone- perhaps a counsellor/key worker at school. It can help A LOT having someone to speak to & confide in. Plus, whoever you speak to probably felt EXACTLY the same way you did when they were a teenager. I know I did & my son is feeling like that now (he's 12).
There are not quick fixes to your 'problem'- just time, self-discovery & realising that you are special & unique.
You are not alone & you are not bi-polar.
Best of luck to you- Life's a journey & you're only a couple of steps in to it ;o)
I sort of have confidence issues; and oh yes I'm in the teenager years.
I bet it's just the hormones lol.