When I was younger, there were some dreams that I chased for years, and then wondered why they weren't fulfilling on the rare occasions that they came true. It took me a long time to realise that they hadn't really ever been my dreams at all.
Because my kind of autism has allowed me to mask my autism a fair bit, there have been opportunities open to me which maybe are not to you; but as I've gotten older, I've slowly drifted into a life much like the one you describe, albeit you have the consequences of your additional disabilities to deal with, and I have responsibilities for my own care that I often struggle to cope with (these are in no way comparable, of course). I get the "lacking ambition, blah, blah" speech from people a lot, because I attempted a life more like theirs in the past, and my masking led them to believe that I could do it. Every time I got a bit too close to that kind of life, my mental health completely collapsed under the weight of it. I still have to make plenty of compromises; I still have some goals for improvement; and I even still have the odd battle with depression and loneliness; but overall, my "unambitious" life is much more satisfying and much less anxious than when I was chasing things that I never really wanted or were way beyond my reach.
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When you are fighting an invisible monster, first throw a bucket of paint over it.