Hello, My Last Period Was November 7th-19th, It Was Due

Hello, my last period was November 7th-19th, it was due December 14th. I had unprotected sex December 2nd and protected sex December 6th. I am on the nexplanon. My period for October was the 12th-20th. And for august it came the 28th-September 4th. Is there anyway I could be pregnant?. I'm also sick, plus I just had my finals for my fall semester of college. I don't know if it's because I'm sick or because I'm stressing. I'm just wondering why my period is late.