Baby hasn’t grown in 3 weeks

Pickle

Baby girl hasn’t grown in three weeks but has a healthy heartbeat and no other noticeable issues. What can I eat to help with weight gain for the baby. I’ve gained a lot of weight myself, but baby is still measuring behind. I see the doctor in two days to talk about the ultrasound results. The tech said not to worry since everything else looks ok, but I can’t help not to.