cumming inside me

so ive been on birth control for about a month and a half, but i havent had my boyfriend cum in me yet. we’ve had unprotected sex but he pulls out just to be safe. he told me he wanted to soon, but im really hesitant to bc i dont want to get pregnant. i know that im on birth control so the chances are small, but i still worry about it. im totally comfortable with it though, but is it a good idea?