im 19 n i have a lump in my left breast i got it checked out twice and both doctors said it was just a breast mouse.. its been three yrs now n i recently noticed my right breast is slghtly bigger than my left..not much of a difference if u take a quick look but i stare at it n noticed it..n im worried it might b a sign of breast cancer.i get pains every now and then but i think its from when i get my menstrual cycle..but what should i do