I think you should just try and be the best observer possible, that way you can give your vet all the relevant information. Then always ask if they think admission would be beneficial.
When Eddison had stasis, it was directly following his neutering surgery. I knew he was in pain, and I knew he was stressed. Taking him back to the vets would have made it worse, so I called my vet and she gave me a bunch of advice, and also a breaking limit. She told me to wait the night, syringing Critical Care, tempting him to eat with anything I could, give the US version of Infacol, and just give him a gentle place to relax with plenty of water and hay. If he wasn't better by morning, I was to fill a script for Metaclop and give that to him. If that didn't work by a certain time, she thought it would be worth the risk to bring him in the office. We had a set plan and followed it, and that was the best course of action for him. I ended up not having to fill the Metaclop script, and he was the least stressed by the experience as possible.
Try your best to know your bunny's needs, log everything that has happened, make sure you trust your vet, and then overload them with information and questions. After that, I don't think there is much else you can do. If you know you're doing your best, then there is no reason to blame yourself if things don't turn out well. You did everything you could and gave that bun so much happiness in his/her life. No need to blame yourself. Just try to learn anything you can from it, and always remember that bunny with love.
I guess the moral of my "story" is to not always choose admission. Each situation and each bunny is different. But if you think admission is best after gathering all the information and talking to your vet, do not hesitate. Just do what you think is right.