I agree with Erie_herps ^ ^ ^ and also, I'm not seeing the "3 hides" you mentioned? He needs at least one of the right size & type on the cool (unheated) side & one on the warmer side- the lack of "security" will make a snake too nervous to eat.
Also, the young prey (baby mice or rats) that young snakes typically consume are mostly digestible- there isn't much waste leftover that the snake needs to expel, since they have much smaller bones & far less hair.
Besides that, we need to know more about what prey you're offering & HOW you're offering it. BPs are ambush-predators that prefer to feed at night, in low light.
What prey you're offering (size & type, live or f/t, etc) & how you're offering (from tongs, drop feeding, etc) are likely part of the reason your snake isn't eating often enough.
Offering prey the right way will embolden the snake to grab & consume the prey, but if it's offered incorrectly, you can scare the snake into refusing to eat. A little wiggle is helpful, but too much, or making it seem like the prey is approaching the snake, is a big turn-off.
Do you feed the snake IN his home? (that's a "must") If the prey is f/t, do you warm it before offering, so it seems life-like? (BPs use their heat-sensing pits to identify & strike their prey.)