Plan b question??

Hi last month I took plan b and my period came the week after I took it. After 3 weeks i had unprotected sex again 🤦🏻‍♀️ I know stupid of me but he didn’t cum at all, but I do know the possibilities of getting pregnant due to precum. The following month I’m late for my period, do you think it’s the plan b making my period irregular? Or should I take a pregnancy test? Talking to my bf currently on getting on the pill and using condoms.