2nd opinion. My friend had that with her son. She was freaking out because they said there was no baby. Obviously there was because he just turned 1!
I would definitely go for a second opinion, but it sounds like you had a blighted ovum.
I think you should go for a second optinion frpm another ultrasound tech or doctor
Did they at least see your yolk sac, but no embryo or was your sac completely empty.