Period late after anal, HELP

So me and my bf recently had anal sex without a condom or any protection. He did not cum and I think his dick went close to my vag once or twice. (This was about 4 days ago) I'm supposed to get my period since its the end of the month and I'm starting to worry cuz it's not here yet. Please explain why my period is 2 days late and if there is any chance that I'm pregnant!!!