It’s really hard to tell a rabbit’s weight from photos unless they are really under or over. To me, in the pics, he looks fine! And he’s SUPER cute!
Feeling is the best way. You should be able to easily feel the bumps of the vertebrae (similar to how the knuckles of you hand feel) but not the boxy sides of them. You should also be able to feel the hip bones, but they shouldn’t feel sharp. If you’re really concerned a vet can give a better assessment. Since he’s already on a pellet-free diet there wouldn’t be too much more you could do anyway! You can also weigh him regularly to see if his weight stays steady.
Bunny breeds vary in body shape, so perhaps your uninformed friends are used to seeing other breeds or wild bunnies.
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The answers provided in this discussion are for general guideline purposes only. The information is not intended to diagnose or treat your pet. Seek the advice of your veterinarian or a qualified behaviorist.