Measuring Small with Big Baby

Kara
Hello! Just curious if anyone else has been told they are measuring small with a big baby. My baby is big- 90th percentile. 4 lbs 8 ounces at 31 weeks. My fluid was high but now is considered normal. Today, my belly measured 2 weeks behind. My doctor said she isn't concerned because I just had a growth ultrasound. Anyone else? Seems strange!