It is always very important to talk to your doctor about any concerns that you have about your breasts or your body. Having said that, it is normal to have breast tenderness at 14, because the breasts are still developing. I remember that my breasts did not reach their full size untill I was in college. It is also normal to have tenderness before your period. As I said, you should talk to your doctor about any concerns that you have. You may also be able to talk to a school nurse if you have one.
Dear uscgrl2036: Breast cancer is extremely unlikely in a 14 year old woman. Breast pain and lumpiness, particularly prior to one’s menstrual cycle is quite common. If this lump is still there after your period, you should show this to your mother. There are many possible explanations for lumps and if it persists may warrant further evaluation.