u/s tech only saw empty sac; dr said it's fine and that they found a heartbeat?! WtF?!

Ka
Went to my first ultrasound. Thought I was close to 8 weeks...the tech couldn't find anything but the sac. Tried vaginal and said the same thing. She said it's either I'm too early (5-6 weeks) or it's a missed miscarriage. I was bummed, but ok with it. Right when I come to terms with it, my dr calls and said that the ultrasound was fine!? She said that it says, " live pregnancy" and dated me around 5-6 weeks?! She didn't see the actual ultrasound, just read the report (live in a small town). We're doing blood work this week...but WTF? 
Has anyone kind of experienced this?!