Oh no my ? why?

As someone stuck with a G cup, I feel your pain. Unfortunately surgery really is the only way to make them smaller when you're not overweight (and you clearly aren't overweight), and I wouldn't recommend surgery until you're older anyway. Good fitting bras that provide adequate support are the only option, really. Like the person above, I wear a bra and supportive tank-top when exercising. As for where you got them from, well... sometimes it just happens.