What Causes Delayed Menstruation, Bright Red Spotting And Cramping?

I am scared. I had unprotected sex with my bf.. the day my period began November 30. Then I had sex December 21 unprotected. But the week before this I noticed egg white cervix mucus which means I was in my most fertile days. And now it's January 7 and my period is about 5 days late and I have light pink yet bright red spotting. I have lots of cramping. I am scared. Do you think I am just late? Because I've been keeping track of my cycles for a while and about every 8 months this happens so idk . I've also been having issues at home so idk if it is just stress. I am nervous and scared I am 19.