condoms or no condoms?

okay girls. I have a question that I feel is probably self explanatory... but it never hurts to ask. so me and my boyfriend have been dating almost 2 years and we have never had sex without a condom. in fact, ive never had sex without a condom in general. I've been thinking about having sex without condoms for a while now and we've talked about not using them since I am also on birth control but we're both paranoid about getting pregnant and don't want to risk it. the truth is not using them would be much more convenient and I don't have to worry about STDs bc were monogamous. how effective is the pill on its own if we didn't use the condom. I never skip doses or at least rarely ever., but sometimes I'm off by a few hours. how high are my chances of getting pregnant if I just use the pill?