tough decisions :(

so my boyfriend is catholic and was raised to not believe in sex before marriage or sex with contraceptives. welll low and behold we had sex, which also means no condom.. we've had sex 4 times, each time eith no condom. He never got close to finishing while inside, we would always stop and finish another way. but i know precum is still a thing. what are the ACTUAL chances of getting pregnant from precum? not high i know, but still there. i told him, definitively, we are either using condoms or im starting birth control, i refuse to be so irresponsible that it ends up for the worst for us. its not our time to be pregnant. have you guys ever had experiences like this?