Sunshine,

All you can do is your best.
your friends might be worried about you, or just not be sure how to act. Or not know exactly how fast you are supposed to get better. maybe they need to be better educated? Or maybe you need better friends....spend time with the people you know you can count on - it's better to have a few good friends than a lot of crappy ones.
Take care of yourself, get those good grades and graduate and take each step as it comes.
Are there any BiPolar support groups in your area where maybe you could meet other people who would understand what you're going through? That might help a lot.