Personally, I think of severity in categories. It's not unusual for some Autistics to have severe symptoms in one area, yet be quite mild in others. She seems like one who is high functioning socially, but has severe symptoms in the sensory arena.
I wouldn't categorize her as mild or severe in a general sense. She's both at once. I see this kind of mild/severe stuff in my own kids. Each of them is mild in some ways, yet severe in other ways. It's quite common.
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I'm not likely to be around much longer. As before when I first signed up here years ago, I'm finding that after a long hiatus, and after only a few days back on here, I'm spending way too much time here again already. So I'm requesting my account be locked, banned or whatever. It's just time. Until then, well, I dunno...