I have encountered this situation many, many times. Believe me, overcrowded bass is the "norm", compared to all other situations.
The best long term solution to this problem is to continue what you are doing. But, be creative with it.
Here's my thoughts.
You have to remove bass. Look at it this way..your lake can produce "x" number of pounds of bass. The head count determines average size. Average size and numbers of bass determines survival rates of young bluegill, backbone of your food chain. By reducing specific size ranges of bass, you reduce competition.
Weigh and measure your bass. You will quickly determine which sizes are overweight, and which sizes are underweight. All thin bass must be removed. But, you will find a larger size range of bass that are healthy and growing. For example, you may find bass larger than 16" to be growing and thriving. That's because bass that size can eat 8,9, even 10" bass. Bigger bass have a food chain. Intermediate size bass don't. Continue removing bass, until you begin to see remaining fish gain weight. As you remove enough, the other bass will grow. Keep a log of fish caught, and watch your log. It will tell you volumes. Better yet, post your lengths and weights in an excel spreadsheet program, and watch the curves change as you catch bass.
Stay with the feeding and fertilizing program. Exception...stop fertilizing by mid-summer. Too many people fertilize too long with overcrowded bass populations. The reason? Allowing the water to clear will allow faster predation by remaining bass, and faster growth rates of the most aggressive bass. In essence, you are trying to create a "balance" of bass, and bluegill sizes.
Here's your bottom line...there is no magic dust or miracle fish to stock to quickly solve your dilemma, without creating another one.
If fishing pressure is the problem, have a couple of fishing tournaments with your friends, or have a local boy scout troup or church youth group come out and harvest fish. It will help your lake and help the group. Harvest, harvest, harvest. That's your goal.

Teach a man to grow fish...
He can teach to catch fish...