Ultrasound Help

Brooklynn • Due April 2020 🌈 👶💗💙

On August 22nd I had my first ultrasound and seen a sac! My levels are over 13000 so I was expecting to see a yolk too but didn't. My next ultrasound is September 5th so I'm wondering what to expect to see. Any ideas? Also the Dr doesn't know how far along I am. What do you guys think? And what should I get to see possibly?