I could use input or thoughts

Hi guys, I had a blighted ovum miscarriage in June and got a positive hpt on September 6th. Based on my LMP, I would be 8w1d today, but I know that my cycles were weird after my miscarriage and the fact that I’m even pregnant means I had to have ovulated late, because my husband was gone for a military training program when I “should” have ovulated. My doctor won’t see me until week 10, and my anxiety was getting so bad that I scheduled a private scan yesterday, since I thought I would be around 7 weeks. The tech only saw a sac that she thought looked around 4 weeks. But it was an abdominal scan, so I’m not sure of how accurately she can measure or know the sac size when it’s early. I’m just super worried because I doubt it can be possible to only be 4 weeks when I got a positive test two weeks ago. Does anyone have insight as to how this could still turn out okay? I think it’s possible to be in my 5th week, just not my 4th. I’d appreciate any input ❤️