UPDATE: Mystery ultrasound! 80 days since last period!

Countless negative HPTs, two negative blood tests - two missed periods, no history of any infertility/irregularity. Went for an ultra sound today as my doctor suspects I may, indeed, still be pregnant (but my HCG just wasn’t detectable) and the tech did a full transvag ultrasound of my endometrium. She spent a lot of time on one part of my uterus, but wouldn’t show me the screen (which I totally understand) and for a brief moment a very fast and loud heartbeat sound came from the ultrasound Doppler.

My question is - has anyone experienced hearing a heartbeat in your uterus? And it turned out you were pregnant? Or weren’t? Thanks, ladies!

Edit: The tech wouldn’t give me any info (this is typical, from what I’ve read). So the imaging center sent my ultrasound pics to my doctor. I should have results back on Monday and I will update!

Update: Its Monday. Just talked to my physician and the results came back negative for signs of pregnancy - but they discovered a large cyst on my left ovary. We are waiting on some more blood results to come back before I go in for a visit. Not sure how that explains missing two (almost three, now) consecutive periods. Hoping and praying that we can come to a diagnosis and I can take the right action steps.