went to see my OB today for an ultrasound and check up. had my first US three weeks ago and the technician told me I was 6 weeks exactly, which lines up perfectly with my LMS and date of conception. based on that, I was under the impression that today marked 9 weeks and 4 days. when my OB started doing the US she asked me if I was certain about my LMS and told me I'm actually at 9 weeks. this makes no sense to me. can someone please explain what's going on?

**Does this mean my date of conception is also off?**