Anyone measuring small??

Kennedy • Married to my soulmate since 7.4.2020!💍💞 We have a 4 year old son, who took a year and a half to conceive! We are expecting baby girl March 11th 2021 after 2 1/2 years of ttc with fertility treatments 💖

So according to my date of ovulation I should be 7 weeks 5 days pregnant.

But when I saw my doctor they said I was only measuring 6 weeks 3 days. I'm a little concerned but they said everything was fine. Has anyone else experienced this??