I agree that the SPD symptoms checklists I've seen seem to be pretty accurate and helpful as far as online symptoms checklists go. I actually printed out an extensive SPD symptoms checklists that I did online and brought to OT. They actually included it in my diagnostic work up.

I think it's definitely worth the research. Even if the symptoms for some reason happen to be caused by something else, the symptoms are still very real, and SPD strategies might be helpful .

Finding an OT who is willing to work with adults or older adolescents with SPD is difficult. Finding one that has experience with adults or older adolescents and knows what they're doing is even more difficult. I wasn't able to find one in my area, but I was able to go to one over an hour away in another state that was recommended to me by a friend on a different forum. The STAR institute's treatment directory might be a good place to start. https://www.spdstar.org/treatment-directory It might be a matter of calling and asking around to find one. The one's I've ended up at are at clinics that primarily serve children. So don't be surprised if you end up at a children's clinic. The one that actually had experience with adults had only served a handful of other adults. I would at least try and find one that has experience with older adolescents, if not adults.

You might need a referral from a doctor. I don't remember if I needed one in my case or not. And just a warning, most doctors don't know much about SPD, or have even heard about it. So if you do have to go to a doctor for a referral, go prepared to explain. Awareness of SPD has increased dramatically in the past 10 years, but there's still a long way to go.