I agree with Bruce's comments. The BG will not travel far for food. That is why one feeder covers about 3 acres max. Your pond is like ours in its shape and size. That is one reason you probably have BG beds scattered around the pond where shallow. There are in essence separate BG populations around the pond with some movement between them. Somewhere I saw info on how far BG will travel it seems like it was about 200 yards. I will check on that.

One way to help in getting all size BG to feed is to use different size pellets. I use Game Fish Chow (has multi-sized pellets) and mix it with high protein fingerling food (3/16th size pellets). I have had no trouble with all sizes of BG feeding at the same time. The big BG take the big pellets first while the small BG eat the small ones. Try feeding in a small (2000+- sq ft) cove with shallow water on 3 sides and some 4 ft water in the middle. I have done that and put brush in the middle for BG protection/hiding.

In any event I think what you are doing is helping more than you may think. By feeding the big fish you are getting more reproduction (higher spawning #s) from them because they are in better condition. In addition the small fish , even if they don't get as much food, are getting some extra nutrients for 2 reasons. One -- they are eating some pellets and 2-- there is less competition among the BG for the natural food sources which means the small ones get more of it.