Could i be pregnant after ending my birth control pills?

Okay i ended my last pack of bcp on wednesday sept.15 and me and my boyfriend of 2 years have been having . Four days after my last pill we did it im almost positve that he didnt nut in me but am i kinda scared that i could be pregnant from previous times from his pre nut probably. I almost never took my pill at the exact same time and always forgot to take it nightly but would take two the next night, so my birth control wasnt balancing i dont think. the night that we did it my period came the very next day and it was extremely early i guess cause i ran out of pills, we do it like every weekend....but is there anyway possible i could be pregnant, i feel very nervous and scared!!!!!