I don't know if this will help you get a girl, but thought you might like a woman's perspective
Women like guys who feel confident about themselves. Or at least act confident. If you aren't satisfied with yourself physically, start taking better care of yourself (women like that and they notice). That might make you feel more confident too.
Something else that is hard to do, especially if you are shy, is to put yourself out there. What I mean by that is going out and meet girls. LOTS of girls. Practice, practice, practice! The more you do it the easier it will seem. Make it your project - to talk to one new girl every day.
One other thing, I suspect that the girls you've been talking to have been in the "friend" category. To be considered serious boyfriend material you have to let your them know you're interested in going out.
PS There are a LOT of girls at school!
I hope this helps.