omg, the same thing's happening to me too, i'm 21 and i started putting on weight last year, like around 10-15 pounds and most of it's gone to my cottage cheese ass, and i'm just graduating in April, i'm scared... :/

it's probably just the weight gain, i went from a B to a C and i read somewhere in cosmo that even if you drop/gain 5 pounds, it's time for a new bra...