Empty sac. 😞

So today was my first u/s. It's been 7 weeks since my last period. 4 weeks since my positive opk. They found the sac but said it's empty. This is our rainbow baby. We had a missed miscarriage last year at 13.5w... found out at 16 weeks. Thoughts? I hope my baby is in there but I'm having so much doubt. I feel broken inside again. 😞 I think I'm done if this time doesn't work out. We used clomid this cycle and had a ovulation u/s so I'm pretty certain how far along I should be. 💔