Baby measuring small?

This mama is stressing a little bit! Had my 20 weeks anatomy scan yesterday and baby's belly and femur were measuring right on 20 weeks but the head was measuring at 19 weeks. They said it could have been the angle and want to do a follow up ultrasound at 26 weeks but baby wasn't moving so I feel like they probably got a pretty good picture. Idk ☹️ I'm a little worried. My daughter was 9 lbs 1 oz when she was born and was perfect my whole pregnancy so I didn't have to deal with this!