5 weeks 6 days pocket of fluid!??

Has anyone had this on an early ultrasound?? I have had some spotting for the last week so my doctor wanted to do a quick ultrasound (a very quick ultrasound) to see if everything looked ok. He said there is one gestational sac that looks perfect with a perfect yolk sac. Then then he said there is a pocket of fluid also?? I asked him if it could be a second baby and he said it “could have been” but it looks like just fluid 🤷🏻‍♀️ I don’t know what to take from that. So... I am having another ultrasound in two weeks and until then I am taking progesterone. Has anyone had an ultrasound like this and turns out to actually be twins?