A lil accident...advice ?

Okay ladies, so my bf and I had a lil accident this afternoon. The condom broke right before he came and I'm not on birth control. Never happened before but I guess it happens to everyone at some point. I'm on day 4 of my period so I know chances are low, but it's still possible anndddd I'm freaking. I went to get plan b so can anyone help me out here ? Should I be doing anything else ? Tips/comments/good vibes/ & prayers appreciated, I cannot get pregnant right now lol thanks.