Im 13 years old and my left breast is bigger than my right, what should I do? Is it normal?

Asymmetry is very common, and is in fact the norm for women. There may be a difference in size and or shape, and this can be quite severe. You can choose to have the smaller breast enlarged with an implant or the larger breast reduced to achieve more symmetry. However, please note that your breasts will continue to develop throughout your life, with a notable stage of maturity once you reach about 19-20 years old. Your asymmetry may correct itself by then, so I suggest you wait until then before considering breast surgery.Please talk to an experienced board certified plastic surgeon to determine what would be best for you. Best of luck.

Do not panic you are just starting to mature and after several years of growth you will be better able to judge the actual size and shape of your breasts.  If there is a difference then, the good news is that it can be fixedDr Corbin