Hi , I'm 17 And Last Week I Had Sex

Hi , I'm 17 and last week I had sex for the first time , when we did it he didnt use a condom but he pulled out and then came . then a couple days later we had sex again and instead of the regular position he did it from behind and also with no condom but it scared me because as soon as he pulled out he came . How would I know if he came inside of me ?