9 weeks pregnant, ultrasound measuring at 7 weeks 3 days?

9 weeks pregnant, ultrasound measuring at 7 weeks 3 days?
Question by *me*:
I had my last period on 11/10/2009, I got a positive pregnancy test on 12/10/09...that would make me 9 weeks and 2 day today. I had an ultrasound done 3 weeks ago at the hospital because I went in because I was so sick (I have HG when I am pregnant, severe sickness) and they said I was 6 weeks pregnant. Well I had an ultrasound today done, and u could see a heartbeat, but that said I am only measuring at 7 weeks 3

9 weeks pregnant ultrasound