Trying to not get pregnant

Okay me and my boyfriend had sex without any protection whatsoever. I'm not on birth control and he didn't have a condom on... Anyways, he put the tip in and that's it. Later when he got home he said he leaked a little and found it in his underwear... We don't know if we leaked inside me or it was just when he put his pants back on... I'm really nervous tho because this happens 2 days before my firtle window, and I don't know what that means.. Is that when I'm ovulating? Please help!!