I know I'm not that knowledgeable about snakes but yours is around the same size of mine and i feed a medium mouse to him once a week and he has a good size lump in him. You would probably have to check if you need to feed every five days or so. But my guess is you aren't heating it up enough. How do you warm the mouse? Do you have a temp gun? Mine likes them around 90 degrees F which is the normal mouse body temp with the head being warmer.