First ultrasound today, feeling disappointed

So I am supposed to be 7w2d today according to my LMP which was Nov 8th. Doc couldn’t get me in until Jan 9th, so I booked a private ultrasound (abdominal) at a boutique place. I just got home and I’m feeling sort of confused/disappointed. I was expecting to maybe be 1 or 2 days behind, but the tech measured baby at 6w5d. Heartbeat was there at 125 and I got to hear it.

Is this normal? Should I just wait for official OB ultrasound before driving myself crazy thinking something will go wrong lol?