Communication Issue

My boyfriend and I always use condoms, but sometimes we have unprotected sex for a minute or 2 before he puts one on. I know this isn't safe, and lately I've been trying to explain to him that I can get pregnant that way, but he always says that its been fine in the past and that I need to just relax. The other day I said no to him until he put one on but he just rolled his eyes and kept going. How can I get through to him