Bugs should be eating primarily hay and a limited amount of pellets depending on age and size. I can’t remember at what age you should start limiting. You can encourage him to eat more hay by putting it in fun new spots. I put a box of hay in the living room and a paper bag of hay in the bedroom and it got Pumpkin eating twice as much as she had been. I think in Pumpkin’s case, she didn’t want to go into her cage to eat, b/c she was forced to spend the night and most of the day in there (she has more room now). Maybe if Bugs runs into the hay in the fun new places he will eat more often.
Small pieces of carrot should be used a treat and used sparingly. There is too much sugar. Maybe try some fresh herbs, like basil, cilantro, parsley, mint, etc. Sounds like Bugs likes sweet stuff, so this is worth a shot. And don’t give up on the other leafy greens. Pumpkin has turned her nose up at someone one day, just to turn around and eat it a week later.
How is Bugs’ pooping? If he’s not eating enough hay, watch his poops to make sure he’s not have digestion issues! Also, the hay helps keep bunny teeth grinded down and if he’s not eating enough, he could end up with dental issues. I