--just because a person doesn't see herself in a helping profession, doesn't mean they don't have empathy. My DS has said he wouldn't want to be a doctor or pilot or anything where "other people's lives depend on you" because of the pressure.
A LOT of non-autistic people would not want a career that was focused on interacting with other people.
--as for "waving the 504 flag:" it's probably a good idea to document these things, in case you need the documentation later to advocate. Especially since it sounds like these are occasional issues and not pervasive, it might help you establish some sort of pattern.
--as an observation: the child you describe doesn't exactly sound "unemotional."

More like an unusual profile, with some trouble managing emotions at times. She also sounds like a fairly typical, driven, anxious, gifted young adolescent. It's hard to know what's causing what, isn't it?