Condom slipped while having sex

My boyfriend and I were having sex and he noticed that the condom slipped off while exiting me. He had not finished, and the condom was dry. The condom was also hanging slightly outside of me (the ring was hanging outside of me). I have missed a few days of birth control.

I stopped ovulating a few days ago.. Do I need to get plan B? I’m really worried.

Update: my BF and I decided that we don’t want to take any chances so he’s buying me Plan B today, and unless my period starts sometime today I’m going to take it. Would rather be safe than sorry. My periods are already horrific so a super period isn’t gonna phase me