Late period

Hey gals, I am in need of some help/advice.

I had unprotected sex a month and a bit ago I had the morning after pill and a few days later got my period, but this month my period in late by a few days and I'm not sure why this is as my period is usually regular? I am just very worried I could be pregnant but I don't see how I can be because I got my period a few days after I had sex.

Can someone please give me some advice or an answer to why this might be?

Thank you in advance xoxox