32 weeks measuring small?!?

Okay I’m really trying not to be all jittery but I’m nervous because when I went to my doc appointment today my doctor told me that my belly is measuring still at 30 cm meaning my belly hasn’t grew since my last appointment. I’m supposed to be 33 weeks tomorrow ☹️ she’s set me up with an ultrasound checkup to make sure baby’s growing okay. I’m so nervous that he’s not . Like what am I doing wrong 😫 I really don’t want anything to be wrong . Can someone please give me some peace of mind