Test results 😟 Please help

So I had a sonogram done Friday and I looked on my chart to see if the posted anything and they did. I was 38 weeks Friday and the sonogram measured 35 weeks and said Kinzlee is weighing about 5.891Lbs. It also said that I have anterior placenta but no abnormal abnormalities. I called the Dr. Monday morning and asked what was going on and all they told me from what I could understand was that Kinzlee is measuring so little that they wanna put a fetal dopplar on me and monitor her. They also said they wanna send me to a specialist to have them look into it... please someone ease my mind and tell me this is nothing to worry about. Has this ever happened to you or someone you know? My anxiety is through the roof now!