Peace of mind

So last night my BF and I were doing stuff and eventually he ended up finishing on my chest. We've never had actual sex before (we're in the middle of a weird moving situation so we don't want to do anything too fast). My question is can you get pregnant if cum were to go over or run over your vulva and be around your vagina? It didn't happen last night, but it honestly gets confusing sometimes when there's a lot of sweat and I don't know what's what anymore. Like I said, he came on my chest last night so it didn't happen, but I'm just a bit of a worry wart and I was wondering for future reference. Thanks y'all!