What I'm reading is that you have a bunch (how many...hard to tell, right?) of very hungry 6-8" LMB and a few even larger in your pond. The key word is HUNGRY. 2" BG and the averaged sized minnow are the right size to be meals to the 6"-plus sized LMB. But, small fish are not stupid and many of them learned to hide pretty quick after being stocked in the pond. Many are still there. If you have a strong population of these LMB still in the pond, your newly stocked BG numbers are going to drop. Hard to say how quickly and how far before the season is over.

Ideally, you need to estimate how many bass are in the pond and what size they are. This is next to impossible to do without a professional electo-survey performed. Without that, an estimate/guess has to be made and then you can start to develop the plan. My thoughts would be to stock large enough BG that cannot be eaten so readily AND would spawn this year to provide forage for the remaining bass. The amount of BG that would be stocked relies heavily on whether you want to try and manage for larger LMB or larger BG. The approach is quite opposite depending on which why you prefer.

Another option is to kill the pond and start from scratch.

As far as oak trees go, they are said to have tannins in them that can cause a fish kill...especially if put in the pond green. One, of your size, in a 1 acre pond is probably a no big deal...key word is Probably!

Fish on!,
Noel