Gestational sac but no baby?

So I had my ultrasound today and it showed the sac and yolk but no baby and I'm supposed to be 8 weeks and 1 day. My doctor explained that I could be earlier than expected like 5 weeks because everything is in the right place. I did labs today to check my hcg levels and I have to do a repeat on Sunday. I've never had something like this happen before so I'm hoping that everything will be alright. If my levels are progressing well then I have another ultrasound scheduled for 6/16. I'm praying that it will work out for me. The waiting and not knowing is killing me.