Supposed to be 7 weeks 4 days measured 5 weeks

Just wanted to see if anyone had any experience with this? I went in for an ultrasound today and was supposed to be 7 weeks 4 days. However, when my OB did the ultrasound she said she only saw the gestational sac and the yolk sac and I was measuring 5 weeks 4 days. She said all the things are there for a baby to grow, but she couldn’t see the baby. It could also be the signs of a early miscarriage. Anyone else have this experience? I’m not very hopeful at this point.