Could I get pregnant?

So I've been on birth control pills for about 10 years now, for irregular periods. But I'm concerned, me and my bf had sex tonight and it's the first time he has busted in me... I'm not taking the pill rn because it's the week of my period (should be starting in about 4 days) can I get pregnant if it's almost my period?? Should I do plan b?? Help!!! 😳