I'm sorry you feel this way. It is very normal for your sexdrive to be on hyper drive at your age. I don't know how you are but it is not uncommon for females to be extra "needy" near that time of the month. Could that be part of the issue?

I hate to hear someone so young talk so down about there self. Self image means alot. I am a big girl and it has some down falls but it also has it's advantage. If you make friends there real friends. It's not cool to like the big girl you have something strong people can see on the outside that lives in the inside to show who you really are.
Some guys don't like boney chicks. A bigger meaty girl is certinly softer and fluffier to sleep with (says some old friends) Now that I'm no example of youth. So be patient you'll find a guy and hope this "need soon passes".