One thing that affects appetite that surprises a lot of people is sleep. If you're not getting sufficient sleep, then hormone that tells your brain that you're full becomes suppressed. Improving sleep routines is actually a very effective method of managing overeating.
Protein is also a biggie. I know you're not trying to necessarily lose weight, but a lot of people who are add a protein shake or something else with plenty of protein to their diets. Protein is very effective in keeping you full.
Lastly, don't feel bad if you eat between meals. God knows, I rarely ever go more than a couple hours without at least a snack. It's not bad for your health. In fact, it can even slightly elevate your metabolism. (Just make sure they're healthy snacks.)