cause of late period?!?

The last time I had intercourse was October 6th and it was unprotected... my last period was November 5-8. It is now 12/21 and I’m fourteen days late on my period. Should I take a pregnancy test? What are other causes? I’m freaking out. My period is very regular and I am not on any form of birth control.

Update: WE GOOD! Thanks guys