Scan

Hi.. I just done my details scan today, as per calculation, my pregnancy should be around 24 weeks.. But just now, when scan, detected that my baby's cerebellum size smaller(around 21-22weeks size). The sonographer told me that maybe there is some mistake in my pregnancy calculation OR the worst case is my baby cerebellum is underdeveloped. I am very worried and sad right now, since there are so many possibilities may affect my baby. I got appointment with sonographer next week to remeasure my baby's cerebellum size,but i think i cannot wait until next week to observe the growth of my baby. Anyone got this experience before?