Older ultrasound machine

Went for us two weeks ago, and only seen yolk sac. Doc said 6 weeks along, went today (2 weeks later) now he says. Embroyo measures 6 week 2 days, and baby hasn't a beat, nor grown! If there is a embryo now and was only sac two weeks ago doesn't that mean there was growth? What did he measure two weeks ago to tell how far I was? The sac? I really think everything is off two weeks, anyone go through this? Omg