What Causes One Breast Growing Bigger Than Other?

sir my age is 20 yrs and i was marriage two years ago. My Right breast is being light bigger than my left one but after marriage i was growing larger i have pain in it and can also feel some kind of hardness inside it eight month ago i had checked it through my GP and he ask me to do FNAC TEST and after that the result came is "Fibroadenosis" then he suggest me some medicine like B-Loop, E-COD. i continue it for 3 month and the breast get some normal and my Gp suggest me to stop the course but now since 2 month my breast is growing again and painfull what i will do ?