growth restriction or just small?

I had to go see a high-risk doctor today because of new diagnosis of gestational diabetes. I am 31 weeks three days. The doctor measured my baby and said he was surprised shes small. She's overall in the 35th percentile and her abdomen is in the 26th percentile. Shes measuring 3lbs 13oz. He said not to worry "shes still in the normal range" and to come back in 2weeks. But I am freaking out that there could be something wrong. Anyone have any insight? He said without measurements from my normal ob visits he can't determine if she's just small or if it could be interuterine growth restriction....please help 😞