Babys tummy measuring small???

Breanna
I'm 38w4d I went in for an ultrasound yesterday because my doctor thought I was gonna have a big baby, turns out his estimate weight is 6lbs9oz and she said his tummy is measuring small for how far along I am....I go back in this upcoming Monday for a non stress test and then again on Wednesday for another ultrasound..any other moms babies tummy measure small? Was everything okay?? I'm a FTM and I'm kind of worried I just want my baby to be okay and I'd be crushed if anything happened to him 😞😞😞😞