I got diagnosed at age 40 under completely random circumstances.
I was getting angry at myself over my inability to deal with social situations, so I enrolled in an anger management course. It seemed logical, until I found out that the class was full of wife-beaters. Still, they taught some good techniques. I had some free sessions with the counselor who acted as the facilitator for the class, that I could access through the facility. It was a christian charity, and had its problems, but they did help me. After talking with me three times, she said, "Has anyone ever suggested that you might have Aspergers?" and referred me to a local psychologist who turned out to be super.
I had previously found really helpful therapists through other sources. They missed the ASD, but I was really well-adapted. I found a great psychologist who also understood holotropic integrative breathwork through the classifieds section of my food co-op, and I made massive progress in figuring out how to achieve my will through work with him. Three of my university professors offered excellent feedback, and I disclosed my autism to them.
The worst would be haters. Unfortunately, it's fun to hate, and they can pop up anywhere.
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"I find that the best way [to increase self-confidence] is to lie to yourself about who you are, what you've done, and where you're going." - Richard Ayoade