Am I pregnant or is it a health problem?

Kacey

I had sex on everyday of my ovulation window (dec9-14) my last period was nov 28, 29 &30th. Now I am on my 37th day of my cycle, period late 8 days (supposed to be december 26th), but I took a test on the 1st of January and a couple days before that and they were negative? Could it be something else that’s wrong?