Baby legs and arms measuring 3 weeks behind at 34 weeks

My baby girls legs and arms were measuring 3 weeks behind, her head and abdomen were measuring on time. I am 5’10 and the father about 5’6. His family is on the smaller side and mine is mixed with tall and short. Baby was always measuring a week behind but at my last ultrasound at 34 weeks she was measuring around 31 weeks. I am so worried and anxious. Dr brought up a possibility of skeletal dysplasia or said she might just be a smaller baby when born. Has anyone went through this. I don’t know what to think.