First sono question!

We went in for our first sono this week and saw the sac but didn’t see the anything else. Doc and tech said I may be early to detect. Last period 7/9 and cycles are usually 30 days. It’s possible I could have ovulated later and they said everything else looked good. I am going back next week for another sono. Originally they told me I was 6w6d but now they think I’m 5w4d. I’m trying to be hopeful and not worry. First baby and would appreciate any

thoughts?