Can a 9 week fetus look 7 weeks?

Maybe but not likely: You have to understand that the usual way to date is weeks from the menstrual period, which is presumed( but not always )2 weeks from conception. But, if a good ultrasound is done and the first third of pregnancy, it should be accurate to within 5 days, not 2 weeks off! if within 5 days, they way still go by the menstrual period or probable date of conception... Talk to your ob! hope this helps.