Breast Cancer in a 13 year old???!!!!?

I am 13 and ever since I started developing breasts (I was a EARLY) bloomer around the age of 9 I have noticed two large soft lumps in both of my breasts...they haven't gotten bigger...they are like DEEP under the tissue and you have to squeeze hard to feel them but I want too know if I have breast cancer because I am really scared..I have had my period since I was 11 also and I am a 36B if that makes a difference...And my grandma had breast cancer...thanks