False negative?

I had a missed miscarriage at 12 weeks Feb 20. I got my first period March 21. I was expecting my period April 18 but it did not. As of today I’m 5 days late. 5 pregnancy tests later and they all say negative.

There are a couple of possibilities for this. 1. I’m not pregnant just late 2. I still had high HCG levels in my system and it’s making the test show a false negative

I can’t help but think #2 is possible. My husband and I def got busy while I was ovulating. (I know this doesn’t guarantee pregnancy). I’ve been having a bunch of cramping since last night. I wrote to my Dr. today but haven’t heard back.

Any ideas or similar situations? I don’t know what’s going on with my body!!