Large breast size trouble?

Patient: Is it normal for my breast size to increase rather go down when i exercise? I’m at a 42F right now and it’s hard on my back even though i’m an average body type. and i’m 17 so it’s even harder when i get made fun of because of my boob size. Am I overweight or is this something I should be worried about? I’ve checked my weight over and over only to find myself getting bigger but my stomach growing smaller. I’m scared that this breast problem might cause something I don’t want such as breast cancer. It’s awful on my back and self-esteem. Any advice would be helpful. Thanks much.

Symptoms: Back aches