Hey Tayten,
I'm no expert but I don't understand lots of small sunfish and only small bass. Somebody may correct me but I think a 12" bass would target 3"-5" fish. The only way I would think it possible for high numbers of small sunfish and small bass would be because of structure. Either too much thick cover that the small fish can hide from the bass to well. Or no cover at all making the bass hunt in open water and giving the panfish the advantage of seeing the bass coming.
My thought is you should assess the current structure situation and determine what you have. Add cover if needed. If possible for you, feed the sunfish a good food to increase their size. If you can put weight/size on the sunfish, the bass will follow. Assuming they can catch them that is.
Again, I'm a pond noob and these comments are only my thoughts. If I am leading you wrong hopefully someone will chime in and set me straight.
