Welcome to Pond Boss!
It doesn't sound like you are doing anything 'wrong.' Some folks here are not too much in favor of 'bucket' stocking fish from other bodies of water, but much of that feeling is based on general assumptions that not every person knows how to identify fish accurately. Further, there can be instances of transferring organisms, both plant and animal, from one body of water to another; there are ways to prevent that such as holding the fish in tanks for a few days in between, etc.
If you removed 40lbs of LMB in the 11" range, we could maybe call that 80-120 actual fish? I'd keep doing that for the rest of this year until you could say that you've removed 400 or so fish, and maybe in the Fall '24, you could find some pellet trained LMB over 8-10" long, and stock maybe 30-50 of them; I say that low stocking number with the understanding that there's already an existing LMB population in the pond that you really are not looking to maintain. The feed trained LMB can grow quickly with a strong feed program, and when they grow, they will begin to eat a different size of bluegill in the pond, larger than what the 11" LMB are feeding on.
You may also want to look into an addition of Golden Shiner Frye from Anderson's fish farm. They ship in the April time frame, but there's usually a waiting list.
If you start feeding the bluegill now, you should start to see increased spawning activity that will help the LMB that you leave in the pond.
Of course, the other end of the spectrum is to nuke the pond and start over.
