Amniotic fluid levels? Normal?

I had a growth scan today, im 19 weeks, and I thought it looked like the sac didn't have a ton of space so I was worried about the fluid being low. I asked my doctor to send me the report. They said the fluid was within normal range....maximum vertical pocket is 3.8 cm. Apparently normal range is between 2 and 8. Even though it's within normal range it's a lot closer to the low end. Should I be worried about this? Attached a pic of my US. I remember with my son having a lot more space than that.