Birth control methods safe enough for him to finish inside.

I'm 20 and I've been on two different birth control pills since I was 14, Trinessa and Vestura, Vestura being the most recent. I had to stop taking it because it was really throwing my hormones out of wack and really causing issues. I'm looking for a new method of birth control. Condoms are a pain, but I'm still using them for now. I'd prefer a method strong enough to prevent pregnancy even if my boyfriend finishes inside. Is there a contraceptive that would allow him to occasionally finish inside me and prevent pregnancy? I know nothing is 100%. I'm just curious if there is something out there effective enough for that. I've considered an IUD but the horror stories scare me! Thanks!