Question I have is why were all three small and was it the same one over and over again (different parts of the pond)
From my experience with a similar pond, green sunfish are probably dominating the water and have started stunting size wise due to overcrowding. It's typical in a small pond that was previously used to water cattle or something or the sort.
If you add some adult bluegill and cater to them with nesting material/sites, structure, fish feed, etc...the bluegill will eventually out perform the green sunfish.
Adding predators such as 10-12 inch bass or 10 inch channel catfish will thin the green sunfish numbers quickly. If you're overrun with green sunfish, which it sounds like you may be, the bass will flourish until they begin depleting their food source. That's why it's important to also establish the bluegill population at the same time. Bluegill spawn multiple times and readily accept fish feed making them ideal forage suppliers for your bass.
If you choose to just go catfish/bluegill you can still have a really nice setup. The catfish will prey on the stunted green sunfish and accept feed too.
Regardless, don't skimp on nesting material/sites, structure, and fish feed for the bluegill. Cater to them whatever you choose to do.
