Check up

I went for a check up. At the time I was 6weeks 2 days pregnant. But during the scan they were not able to see my water bag or baby so they did virginal scan. They only saw a water bag and not able to see the baby. So the doctor ask me to come back 4th dec to scan again. I am worried. DiD some one had the same experience or anyone can advice me. Till then I am having a bad mood swing and not able to be myself.