She's an architect obsessed with structure and creating a perfect world. She may be a little OCD, but I don't see her as autistic. And sensory overload doesn't really have to do with Symmetra, I don't think she could handle the fights if her senses were easily overloaded. If anything, I'd think she had extraordinary senses to be able to concentrate with her turrets and portals and everything. She's an overly organized architect obsessed with the image of a perfect world, but I don't see her as having any disabilities because of it.
Isn't autism a social disability? I haven't seen anything yet so far that would be any indication that she has problems communicating, and if aspergers is just a less severe autism, than in your theory she still may not have autism at all but just aspergers. I don't see her having either at all though.