When I was 9 weeks along they told me July 19. & according to my LMP its July 19. When I had my 20 week u/s scan they told me July 23/26. My doctor goes by the 26th , I say the 19th. Baby going to come when she's ready anyway.
Once you get further along Amd theu do another ultrasound you'll be able to know which one to go by. But for now you can go by what they say you are which would be 9 weeks.
I think the ultrasound is more accurate especially in the early weeks. . .but I mean really your due date is just an estimate. Some ladies go over. Some go earlier. Just depends on when your little one decides he or she is ready. .did you ask your dr about that?
I would think your dr would go by the ultrasound. Ultrasound measurements are usually the most reliable. I would bring it up at your next visit. I give or take a couple weeks from the date they give anyway.