As a keeper and someone who is more passionate about retics than most the true answer is they are giants for a reason. If you want a smaller retic you get the locales that are smaller and you feed them normally. I follow the same feeding schedule that is proven to work by Shane Castello.
You can feed retics every 7-10 days with no issues in life. You just need to ensure the prey items are large enough. 25-35% body weight during the first year is not uncommon for your food size. However mainlands should be fed every 4 days 25% of their weight for the first year. Super dwarf locales will eat a lot more food than a mainland in reality but they metabolize much faster allowing them to still not grow as large. All growth is related to food availability though. And "maintenance" feeding a retic is not ideal for the snake.
Anything else just ask or join us over at the retic nation.
Cheers