Need some insight

So my period was due yesterday- No show. I’ve taken probably 10 tests in the last week and I’ve had a few that I believe are vfl but I may just have line eyes because I had a FRER yesterday morning that was negative, and a Wondfo this AM that was negative. My CM before AF is usually really thick/creamy and it’s been watery for the last couple days and it’s starting to pick up now as well. Also the last 3 days, I’ve had a lot of period-like cramping and non-stop headaches. I usually start cramping after my period has already started and i rarely ever have headaches. I’m just curious, it is possible to get a BFN when you miss your AF and get a BFP a few days later? I have very regular 29 day cycles. My doctor wants me to come in and get blood work done in the AM if still no period, but I’m just hoping someone’s been in a similar situation and can help put my mind at ease. Thanks for reading!!