am i safe ?

so recently my  boyfriend and i had sex w/o a condom he did not finish in me and i am on birth control. however i have heard that pre cum can cause pregnancy? i know it is extremely rare because i am on birth control and the pre cum often doesn't have sperm or heathy sperm but i just want to ease my mind of any possibility of pregnancy. please tell me your thoughts, thank you. Also, i take my birth control everyday at the right time, the only thing that has changed is that i moved it an hour back and this is my last week of active pills.