Is it possible to have water bag in uterus without having pregnancy

Fan Question
Is it possible to have water bag in uterus without having pregnancy?
I had my check up this week and my doctor tells me that there is a bag of water in my uterus and their is no sign of pregnancy yet but i am also feeling low mostly like vomiting or lose motion . What does this means i have check up next week to see if their is any sign of pregnancy . Can anyone knows about this what does it means i am pregnant or not or their is any other issue i am really worried about this .

Yes, I think it is possible to have a sac and not have a baby. I am sorry