Sooooo

My nipples are extremely sensitive/sore for the past few days. My husband finished inside me last Monday or Tuesday. I'm on birth control and take it as best as can but when this happened I had just finished my period and only started taking the actual pills.

I know there'd always a chance of pregnancy but I'm wondering how big a chance? Like should I kinda warn him or what?

Other than the sore nipples that's the only thing different happening that could possibly be related to being pregnant.