Ashley, the symptoms you're showing sound perfectly normal for a girl your age. Going through puberty will bring lots of changes to your body, and these changes sometimes produce odd feelings in your breasts - tingling, soreness, a feeling of heaviness... And it's not unusual for one breast to grow more quickly than the other. Breast cancer at your age would be HUGELY unlikely, and the symptoms you describe aren't cancer symptoms. I'd suggest going for a physical sometime soon, so the doctor can explain in detail what you might feel like, and what it signals, in the next couple of years.

And - good for you, being aware of changes in how your breasts feel. This is something that we as women need to think about our whole lives, so you're showing good maturity, at your age, to already be paying attention. Good luck! - PJH