Baby is showing 6 weeks 1 day?

Alexandrea • Anastasia 10/30/2015👶🏻 My Lovely Husband 3/24/2017👫💑 Baby #2 2019👶🏻

I had my last positive OPK January 23, got my first BFP on February 1. February 18 had my first ultrasound, we couldn’t really see anything, lady said she thinks it was a yolk sac. She measured me 5 weeks and 4 days which seemed right to me because of my last OPK. Today had my second ultrasound I would of been 7 weeks pregnant but she measured the baby and baby is showing 6 weeks and 1 day.

I’m so confused if I’m 6 weeks and 1 day that means my conception day was January 30 but I had a positive pregnancy test February 1? Should I be concerned? Baby did have a heartbeat of 110.