I was diagnosed with ADHD and started on medication at 12, but not really told anything about what it meant for me or how to deal with it, and when I was 18 -literally when my parents dropped me off at college- was told I was autistic
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Its made me completely adverse to making plans. Like, I looooooathe making plans any further out than a few hours from now, because otherwise my life is rendered inflexible and anything that could upset my plans are means for monumental emotional turmoil.