Need help😔

Kala
So my LMP was December 24, I went in on February 16 for an emergency US and was told that I was measuring at about 5 weeks and 5 days.. but on March 1st at my follow up appointment I was told that I'm measuring at 6 weeks and 5 days, which doesn't add up. I was able to see my baby and hear his heartbeat but I' am very concerned at this point. Either the doctors are wrong or my baby isn't growing as he should, have any of you ladies experienced this?