Confused 🤷‍♀️ but pregnant

I’m happy 😊 because I definitely got my positive and confirm with a hcg level of 4,500. But in my first ultrasound dr was unable to see anything. 😔 they kept saying is early but my lmp was January 29 which will make me 7 weeks. I know I ovulated on feb. 25 .

I’m not sure what to think. This will be my first pregnancy 🤰 but I’m scared 😟 that no baby in the uterus yet.

Any thoughts? Or experienced ya can share ?