Condom Slipped off, should I take Plan B?

Some info: I have PCOS. VERY irregular periods. My last period was Feb 9-15 and my next one is March 22-28.

My boyfriend and I were having sex and I felt something was wrong with the condom so I told him to stop. I pulled the condom out of me, a little bit of it was hanging out. He says that he saw it was on his dick but I told him I would get it, so when he pulled out, the condom fully came off inside me.

Do I need to take Plan B? He says I’m fine and he didn’t cum nor was he even close to it. I said precum, but he says there’s no way because the condom was halfway on when I stopped him.