Baby head measurimg small

I am currently 34wks and 1 day did a ultrasound last week they told me my baby girl's head was measuring small 😔. So today I had an appointment with a maternal fetal medicine doctor and she told me my baby head was measuring at 30wks and a few days but her brain and everything else is measuring fine. Every since I got the news I really been feeling stressed and depressed about the situation because me being a first time mom you just want you and your baby to be just fine through out the pregnancy! but has anyone experienced this before? how did you coped? I need advice..