How do I know he came?

I was with this guy and he'd been drinking. he wanted to have sex and I did too. We started having sex and after a bit he stopped. I am pre try sure I felt that little twitch a guys dick does when they come but I dunno. I asked if he came and he said no he couldnt cause he'd been drinking? later that night we had sex again and after a little while he said he couldn't come either. So my question is what're signs that he did come inside without me knowing, and can drinking make you not be able to Come? He he said he couldnt couldn't finish with condoms so we didn't bother and I said let's do pull out. He already has a daughter and Ive got 2 kids