Please Help! Ultrasound at 6 Weeks and 3 Days

I got an abdominal ultrasound this morning at a facility that just offers scans. I couldn't wait to see my doctor because I'm at risk for ectopic and wanted to be sure everything was okay. They saw the gestational sac and yolk sac, but couldn't find the baby. The tech said that my gestational sac measured at the right size for being pregnant for 6 weeks and 3 days, but that the babu may be younger than that, and thus difficult to see. Should I be worried? Has anyone else's baby been shy during an early ultrasound? I see my OBGYN this Friday. I hope he'll do a scan then to set my mind at ease. Thank you so much for your help!