At 9wk 5days (Feb.3) scan by transvaginal fetus measured 2.75cm, 13wk 2days (Feb 27) abdominal scan fetus measured 7.06cm CRL.. Appropriate growth? Could these be off 3wk+? How accurate? Due 9/2

Follow up visit. Based on this limited information your sonograms were 3 weeks apart and the fetal measurements shows 3-4 weeks of growth. This sounds appropriate but it would be prudent to schedule a follow up visit with your doctor to go through the details and specifics.
Ultrasound dating. The earlier the scan the less normal variation and is the most accurate for estimating your due date. For an average size of nine weeks five days, the normal variation is a matter of days, and would be the most accurate for dating your pregnancy. I am confused with regard to the dates of your ultrasounds and the size of the measurements. .