No Period, but Not Pregnant?

I lost my virginity on New Year's Day, and my partner and I used a condom and he pulled out, just in case. My period usually runs a little late; however, according to both of my period tracking apps, it was now almost five days late. I have bought a total of five pregnancy tests since I lost my virginity (with the most recent being today), and all of them have come up negative. It is now over a month later, and I still haven't gotten my period (17 days late, according to eve). Should I be concerned? Has anyone else experienced a late or missed period after losing their virginity? Should I go see a doctor? Thanks!!!