What do you think is going on?

I had my first ultrasound today. Based off my last period I should be 6 weeks and 1 day. In my ultrasound I was estimated 6 w 5d but we could not see baby. We saw a yoke sac in one sac but also seen another sac that was empty. She didn’t see a fetal pole either. I’m making an appointment with my ob soon as my insurance goes through so for now I’m going back to get another ultrasound in a week to see if there has been any changes. This isn’t my first pregnancy I had a perfect healthy pregnancy with my first and was able to see and hear her heart beat at 6w 2d with my first ultrasound.