plan b

i haven’t been on birth control for about 6 months now (don’t have sex often so it hasn’t been a priority of mine right now) i had unprotected sex and he came inside of me. this was Saturday and i didn’t take plan b till monday evening. i was suppose to get my period that sunday but it didn’t come. i’m usually irregular so it wasn’t a red flag but now i’m about 5 days late. is there a chance i could be pregnant? 😩