Period 19 days late. Covid or preg?

I had covid in December. I had my period for december while I had covid. I was supposed to get my period again on Jan 21 which was 19 days ago, but it never came and I still haven’t had it. I took 2 pregnancy tests, both negative. I took it at night though, are those accurate? Is it just because of covid effecting my body? I had it very mild though.