Just need some reassurance.

So my bf and I had sex three days before my period. No birth control used, he came in me and I was on top position. Since it was three days before my period I knew the chances for pregnancy were low. But today I didn't get my period so we decided we still had time and I took some plan b. I'm still very scared though, I took the pill at 11 am and haven't really had any side effects.