If you really just have hybrid bluegill and only hybrids in your pond, you need to add some native bluegill. Otherwise, your bass won't have anything to eat. You need to do this NOW, or sooner if you can. Also stocking some fathead minnows (10 lbs or so) will help tide your bass over until your bluegill spawn. Stock minimum 3" bluegill, bigger is better, and they may still get a spawn off.

Bass generally don't feed train well, so feeding your lake is only feeding your hybrid bluegill. Sounds like they've taken to the feed well, though.