I can't help to notice that this may be a gender-correlated personality trait:

• All the people you cite that gave you positive advice about being a sidekick are female. In a community which is almost 90% male this seems pretty difficult to get by chance.

• You're a nurse, a typically (~90%) female job. Nurses are natural sidekicks to doctors.

I suppose that the fixation for being a hero of the LW community that makes you feel out of place may be the result of it's mostly young male demographic. Maybe young male nerds are particularly prone to that, since they grow up fantasizing about being Frodo or Luke Skywalker or Harry Potter, and they have an inflated ego due to the "smartest kid in class" effect.

Maybe female nerds are more oriented towards the sidekick role because they are more likely to be biologically programmed to attach themselves to an alpha male rather than seeking dominance/leadership roles for themselves, or maybe females are just more realistic than males about the actual chances of becoming the hero who "saves the world" because they have less testosterone-fuelled hubris of the youth.