Plan b issues

Hey girlies! So I recently got off BC and had sex and of course after going a month without seeing my boyfriend he came in me 🙄😭 So the next day we got plan b, but I still haven't gotten my period yet. It's been about 4 or 5 days. And I'm due for my period anyways. Could it be my cycle is thrown off because I'm not on BC anymore? Or was the plan b ineffective? Could it be he possibly came in me after I took it??? I'm just so confused and nervous. Should I take another pill in case? :( help please