In my opinion you don't have to worry much. Your baby is doing fine.
The initial measurements are used to rule out any growth retardation. Even though your gestational age
by calculating from Last Menstrual Period was not mentioned I don't think there is any growth retardation. If there was any, the Radiologist
would mention it in the report and I don't find any discrepency in between the readings.
The position of loop behind the back of neck is not a thing to worry. If the cord is seen around neck that too tightly wound then only it becomes something of a concern.
Wish you a safe delivery and happy motherhood.