It's not as uncommon as you would think. At 19 I'm still living at home, rent-free but paying my own college tuition (and by that I mean racking up my own college loan debt). Stay if you need to, moving out before you're ready is only going to be damaging in the long-run. My cousin, who's 23 going on 24 and doesn't even have AS is still living at home, and he's not even going to school (of course, he's also a bit of a layabout, but that's rather beside the point.)
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"Survival is insufficient" - Seven of Nine
Diagnosed with ASD level 1 on the 10th of April, 2014
Rediagnosed with ASD level 2 on the 4th of May, 2019
Thanks to Olympiadis for my fantastic avatar!