Is It Common For A Gestational Sac To Be Empty If I Was Around 5 Weeks Pregnant When Scanned?

Hi - I’m not sure how far along I am but I had an internal scan last Thursday that said my mean diameter of my gestational sac was 11mm but it was empty. No yolk sac or fetal pole. I’ve been told to come back in 10 days - I’m back on Tuesday but I’m so worried. Is it common to be empty at 11mm in size? They couldn’t date me properly yet but I think I was 5 weeks when scanned. I just keep googling and reading different things so I’m very worried.