Itchy breast?

I'm 16 years old and my boobs get really tchy near the nipple, but the left one always seems to be more itchy. The left boob is red near the nipple and has little bumps on it. The right boob is itchy but not as itchy and it's not red and doesn't have any little bumps on it. I am sexually active with my boyfriend of 2 years and 9 months, but just started have sex. We use condoms everytime and we also use the withdraw method with the comdoms as well. So he never "expoldes" in me. So I'm not pregnant.  Could it be the bra I use or are my boobs growing.