Better late than never...diagnosed at 18
I was diagnosed when I was 18, at school abroad. I had been seeing a psychologist for some issues I was having adjusting at school, and after a few sessions she handed me a checklist and asked me to fill it out.
Coincidentally, I had at the same time been reading a novel where one of the characters is a deaf little girl mistakenly diagnosed as autistic when she really has SPD. These two events totally flipped my world over. I realized I was like the girl in the story (to a much lesser degree, thank G-d.)
I realized that all my little pet peeves and strange habits actually stemmed from one source. For example, it was well known in my family that no one could sit close to me; I just couldn't handle it.
As a kid I would flat-out refuse to wear clothing if it was itchy and didn't have the tags cut out, and I would always turn my socks seam-side out. To this day I really dislike tights. And sounds- I always thought I just had keen hearing, but it was strange because while someone could be talking to me and I would have trouble hearing them I could at the same time hear with perfect clarity the kid chewing gum three seats away.
And there's so much more...When my therapist told me "Look, this is what I think you have" it just made so much *sense*. I had totally not realized that all the things that bothered me were related. When I returned from abroad I started OT, and its really made a huge difference. I no longer flip out if someone near me is chewing- I don't like it, I will move if possible- but I can usually handle it. My family tells me I'm calmer and not so nuerotic. And I've caught myself getting irritated or self-regulating (bouncing my knee is common) and tried to figure out why and I'll realize there's a clock ticking in the back of the room.
There's still a ways to go but I'm just glad it was caught at all and not just dismissed. Now I see how it really did affect my whole life and I'm hoping the OT will do the same- for the better.