Measured 2 weeks behind (7 measuring 5)

Hey everyone. I was just curious if anyone has had any experience with this. According to my LMP I should be 7 weeks 4 days. However, the OB did an ultrasound and only saw a gestational sac and yolk sac measuring 5 weeks 4 days. She said it looks like everything is there for a baby to form, but she doesn’t see a baby yet. She said it could also be the signs of an early miscarriage or my dates are off. We were trying for this baby, so I took OPKs and everything. Being 5 weeks 4 days means I would’ve ovulated after I had a positive pregnancy test. I’ve had zero bleeding or cramping, I’m not very hopeful at this point. Anyone with similar experiences?