“Fitting in” is not nothing, even if it seems like bullshit, you can train anybody to do a job but not to be part of a particular team. My old boss used to say he had trouble hiring accountants because so many were quiet and he needed someone who would stand up to him, he was sort of intense and could be intimidating. You do have to “fit” in some way to be a cohesive unit, and I imagine that’s a lot more important in an ER than a back office.

Your post sounds like you are not aware of your own behavior as much as you are aware of everyone else’s. It’s entirely possible this is just a bad fit and you can find a job that suits better (I have always done better in the wild west environment of startup companies than anyplace with politics and bureaucracy) but if the same thing keeps happening, it’s you.