Hi,
You've got a really good setup and very healthy looking plants. They still have a while to go so I'm sure they will keep building over the next weeks. However some strains just seem to yield less than the breeder says. I don't think their lack of size is from you, as you've got good lights, a nice nutrient lineup and a soiless medium with a comfortable environment. From what I can see the majority of everyone growing this strain on GD is reporting low yields.
I think you'll wind up with small but dense little nuggets.
Great job on the grow so far. Happy flowering. ✌️