Anyone ever had this happen?

I had one ultrasound around 6 weeks and 5 days and was measuring on time and saw the heart beat. It wasn’t an “official” ultrasound. This was just to confirm a heart beat due to bleeding/cramping. I was supposed to be 8 weeks 6 days on Thursday when I got my ultrasound done. When the tech was doing it I watch her measure from head to toe, and it came out exactly 8 weeks 6 days. She said my due date was still at May 19. However, my doctor just read over the ultrasound and looked at it. He said my due date is actually May 10 now and I am further ahead than I thought by a little bit. This has never happened with my other two pregnancies. My original due date of may 19th even lines up with my period so idk I’m confused because I also saw the measurements on the screen. Anyway, I know he’s the doctor and knows what he’s doing so I should trust him. Anyone had this happen,