Sex For The First Time

So I’m 16 & I want to have sex with my bf. I’m fully ready and Ik I want to do it soon. I’ve asked my mom about BC but she does not want to put me on it cz she doesn’t think I need to be on it at this “young” of age. So what r the odds of me getting pregnant if I have sex using a condom and he pulls out before he cums?? Helppp