Oh my dear, please don't question yourself. This is the nature of bunnies. They are hard-wired to hide their pain. The one thing meant to help them survive can be their biggest downfall. It is nothing we have done or not done. It is nature.
All the information says that steatitis is very rare so it is not likely anything even a vet would be looking for. You can't blame yourself for not seeing something that a professional wouldn't spot right away.
I thought (as did my vet) for months that Mimzy had just been getting more creaky and restless with his spondylosis (diagnosed with early onset arthritis at three years) and that his ears bothering him was wax or mites we couldn't find or his nose trouble was just dust or mold or some other allergen. And it could have been any of these things, but it was early warning signs of EC, I'm pretty certain now. By the time he displayed signs of head tilt it was too late to stop it and now he is permanently tilted. Any difficulties he has from here on out are because I didn't recognize the pattern, I didn't have his anti-inflammatories at a therapeutic level and I could not get him to the vet quickly enough to get abx into him before major damage was done. But I have to remind myself that my vet didn't see it coming either.
I've spent a lot of time beating myself up for all that and while it's a different situation overall from Honey's, it does not make either of us any better to be angry with ourselves for what we either didn't or couldn't see.
I would know a bit better now what he was going through, but still they are just too good at acting like all is 'normal'...or we just think they are getting older, slowing down.
I wish I could give you a huge hug, I know you must be hurting so terribly and I wish I could do something to ease the pain.