when I was younger I would go on diets and lose weight but my boobs would stay the same. For some reason I never lost any in that area.
Gaining weight can cause your boobs to grow... You could try to lose some weight 10-15 pounds and see what happens.... For a lot of women and men, the more weight you put on, the bigger your but and boobs will get.
Correction : I am sorry the size is an N in USA not M.