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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College. And I think I actually developed co-morbid mental illnesses (depression and anxiety) that led me to finding out the root cause (ADHD-PI).
More info: I'm pretty positive (through internet rabbit holes) that I was what some in the psychology community call "twice exceptional". I fuckin' crushed school all the way into (and most including) college. Because of that, my numerous (in hindsight) obvious symptoms were ignored/let go because I was "successful". The closest is 1 teacher of a different class in my grade (not even my own teacher) told my mother I should be tested for autism because of how upset I would get at deviations from plans (again more likely my ADHD). That all came crashing down when I just... fell apart one semester of college. I gained weight and was at my heaviest ever (and I'd never been skinny) and I failed my only class in all of school (still the only one). If I hadn't been encouraged by my partner to get help (and then do some self-diagnosis to fight my way to the ADHD test)... let's not go there.
Still really struggle with things that I never developed healthy coping mechanisms for because instead I just... lived with them most of my life (and all of my formative years).
It kiiiiiiills me when things are different than planned. It makes me super sad or angry when it happens, but it's not an appropriate response so I have to channel it inward.
Does that make me perfect at keeping my own commitments? Oh, heaven's no.
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.