Hi there. Well, it is hard to say. Breast size is dependent on genetics, hormones and fat. When did you go through puberty, get your first period? Breasts change throughout life-- pregnancy, aging, etc. Gain weight, your breasts will grown. Lose weight, they'll shrink. Get pregnant, they will grow. Nurse a baby, they will grow. When finished, they will shrink.
I would try not to get caught up in something like breast size. Who is that for? Guys?