TMI!!! What does it feel like when a guy cums inside?

I'm stressing out that my boyfriend might've done this, last time we had sex, and a few times before that, but I'm not sure what it feels like. I don't want to have kids at the moment but he really does. He's told me he's willing to wait but he's alway telling me "I'm goin to baby you up soon" so I'm worried that he might've came inside me. I'm not ready to have a child right now because I'm only 20 and no job, so you can see how bad that would be to me. I've felt it really wet down there at times when he finished and I'm not sure if it is me or him. Can someone explain please? I'm not that experienced in this area so I'm still learning.