Being told she is too small, any advice?

I have been seeing a high risk doctor because I have extremely low Pap A. She has only been a little small each time about a week behind for the doctor didn't seem to think it was a problem. Yesterday she weighed 1.4 pounds and I am 25 week and a few days. This seemed about right to me but now they are saying I have to be seen every week and that her waist and femur bone were way too small. Is anyone else experiencing anything similar? I would love any advice I could get. Thanks!