Sex during period

I need some questions answered please. I had sex two nights ago while I was on my period and I think he knew I was on my period but I'm not sure. I know that he did cum inside me. I wasn't educated on anything that has to do with having sex on your period so could anyone help me with anything that has to do with sex during your period? Like if you could get pregnant or anything else with it? Please and thank you :)