Doctors had an inaccurate read at my first ultrasound!!

Giannie

I went to my first prenatal appointment on February 1st and they did an ultrasound and told me my baby was 7 weeks... when I go back 2 weeks later they do another ultrasound and tell me they did an inaccurate reading last appointment and I’m really 6 weeks! That’s a whole month difference... has this happened to anyone else? And advice on what to ask or do?