Missed AF but BFN

Kr

I’ve had subtle period cramps for the past 2 days, but no AF, and pregnancy test showed BFN. What is the latest you guys got your first BFP after AF? I’m due to have endometriosis surgery on Friday (02/19) but i have to be finished bleeding before the doctor will do the surgery 🤦🏻‍♀️ it would be a blessing if I could be pregnant and not have to do the surgery, but I’m worried that AF is going to show up just in time to force me to reschedule. My AF is very regular. I don’t know that I’ve ever been this late before...

What do you all think??