help!!!

so me and my boyfriend were having sex the other day and didn’t realize the condom fell off and got stuck inside me... i took a plan b the next day, just wondering if i could still be pregnant? i was supposed to start my period two days before we had sex but sometimes it’s late, and now i’m 10 days late. i heard that plan b can affect your period but i wasn’t sure how true it was. just wanting to know if this has happened to anyone else before and what happened??