Your comment about chewing bothering your DD caught my attention, as did you saying she doesn't like to sit too close to others. (Possibly because she can hear their breathing?)
I would definitely have her tested for AS. She may just be highly-functioning and so is flying under the radar.
You may find this thread interesting:
Hypersensitivity to Little Sounds My DS, now 7, couldn't walk through a parking lot on a quiet Sunday without covering his ears when he was younger. He's outgrown that now, but I still see him covering one ear on occasion. The doctors all say he has fine hearing. When I question him about it, he just says it (the sound, sometimes too faint for me to hear), is too loud.
AS is something I believe runs on my side of the family, though nobody has admitted to it.
