Sore Breast!! Two days after sex...

Two days ago I had sex with my boyfriend and now my breast are tender. Am I over reacting? Could I be pregnant? Does it work that fast?  He didn't pull out or use a condom so basically he nutted in me. I have PCOS and he always cums in me but I haven't gotten pregnant. It's just odd that my breast are tender because my next period starts in 13 days according to glow... Help!!