Update: I still have row 1 and column 1 on for testing. I removed one of the clusters in the first column and tried lowering the resistor values of 300 to 150, 47, and no resistors. The brightness obviously goes up as I go down in R, but even at no resistors the cluster is not as bright as an extra "test" cluster detached from the table and connected to a 9V battery.

I used this extra cluster connected to a 9V battery for my intial table construction, as it was bright enough for the glass, and I assumed it would be getting 12V, so I knew for sure it would be sufficient.

Any ideas?