With such a deep, quick drop and a lot of pads lining the shoreline, that may be part of the issue... not enough good BG spawning area. It doesn't take a lot of space, but you may want to look into clearing some shallows (out to about 4' deep) a bit so the BG have good bedding area with ample sunlight. It will only help the entire food chain. 200 3-5" BG will definitely increase your recruitment if they have a place to make babies. They are a bit more expensive if you plan to purchase, tho.
I added 300 small bluegill and redears (1" to 3" )last month - haven't found a source that has larger ones in stock. The one end of the pond is a bit shallower - drops from weeds into 5'-6' of water - catch most bluegills in that area. Also caught the big bass there.
