Measuring 2 weeks behind

I know the exact night I conceived (11/23/24) and went to the ER as I was having stomach pains, lost some of my pregnancy symptoms, and had been spotting some. They did an abdominal scan and couldn’t see anything, so they had me to a trans vaginal ultrasound.

I was expecting them not to find a heartbeat because of my symptoms, but they found one. However, I went in thinking I was 9 weeks, 4 days and she said I’m measuring 7 weeks, 4 days (gestational sac) and 6 weeks, 4 days yolk sac. The heartbeat was 138 and she said all looked normal. I had stopped spotting too. But I just spotted again today. I can understand being 3-5 days behind (due to ovulation), but 2 weeks? My app calculator has my due date as 8/19, and the tech told me it was 9/11. Anyone else had anything like this happen?