Stomach not filling during anatomy scan

Has anyone ever experienced this? I cant find many stories on this and ive been a wreck. During my anatomy scan at 19 weeks they told me babys stomach didnt fill with amniotic fluid at all during that hour and they also wrote down "stomach appeared small".

The ultrasound tech said babys bladder was filled and the amniotic fluid levels were normal also so I shouldnt worry. But how can you not.. Anyone have this happen and have the next scan turn out fine?