Font size 17 is fine. I'd prefer it if people showed more originality in their font selection, actually, because it makes it easier to tell who wrote what when skimming a topic.
I think, as much as some people with Asperger's syndrome prefer sameness, some do enjoy a little unpredictability. I can't say I'm completely free of routines myself, though. Just ask my roommates about my morning and night routines.