Should you just be happy with what you're catching? Never. I don't think anyone on this board is every 'satisfied' and is always looking to either improve something or make sure that whatever you're doing today aligns with you goals for tomorrow. So not nit picking. Its your pond and your fish!
Tilapia would help. If you have them already more wouldn't hurt. BG and tilapia both bread like crazy. I'd be interested to see what size BG you have in the lake and if you have enough and enough size. I'd also consider a feeding program for your forage if you want to really see what you can do.
I think you should think about removing some of the smaller/skinnier predator fish. There are lots of posts on here about culling. I'm sure some of the others will give their suggestions as well.
(see articles like:
http://www.bassresource.com/fish_biology/big_bass_ponds.html)I'm interested in how much a culling/forage/feeding program can help in a semi-private/linked lake like this. Ultimately I think if you get a few of these fish a little larger they'll actually start culling for you eating the 12" bass.
Ultimately, to get big bass you need them to have enough food to get bigger. That means either limited bigger fish so they have enough food, or enough food to support the base of fish.
