At 6wks my ob could see a sac but he said that all he expected to see. At 10wks I could see a blob anda heartbeat. I think he may have had an older machine.
Mine was at 6 weeks and looked like a blob to be honest but they found a heartbeat and this baby was in my uterus not in my tube so that was the main thing!
At that stage you will see a sac, yolk sac, and a teensy fetal pole and heartbeat via ultrasound. They do them trans vaginally at my office at that stage.
I hope it goes well for you! I would be very nervous as well. I miscarried my first baby, and an empty ultrasound screen can be heartbreaking.