It could be like Rhaposdy said, your still growing.
Do you come from a big chested family?
I haven't gained or lost weight in the past two years and my boobs keep growing!! I went from a C to D to DD in the past year in a half, I fear they won't stop!! I think by the time I hit 25 I may just be all boobs!!
All the women in my family are big chested, on both sides, I actually have an aunt and a great aunt that had breast reduction surgrys!!

It will be okay, although I understand the frustration, I've just learned to accept my breasts and the fact that it's just a part of my body, I was shocked when they grew like that because I went through puberty really earl and thought at 18 my body would be done growing.