EMERGENCY PLEASE HELP!

Last night I has sex with my boyfriend. He did not cum but when we took off the condom, we noticed his penis was really moist. I asked if it was normal and he said that it was probably just lube and my cum. Immediately, I panicked. And asked how that could have been my cum if he wore a condom. I told him to blow up the condom like a balloon and we checked it. The air wasn't coming out. So I guess that means no hole?!? I'm not sure. Should I take a plan b just in case? Btw I have a high chance of pregnancy for the next few days according to this app. Please leave you option or what you think I should do.