I think quite a few adults realise they have ADHD when they go through the process of having a child diagnosed for a disorder.
My blinding light moment came about through reading an article in a woman's magazine. A story about a mother who realised she had it when her child was being diagnosed. I got really excited as so much of her experience growing up was just so familiar! And then, in typical for me fashion, I somehow just forgot about it. The moment had passed and other stuff took over. A whole two years later I came across that magazine in my car and it all went on from there!
Hiding, your description "If I follow my usual pattern I'll obsess about this for a few days more, including constant googling and boring anyone that'll listen (then regretting it), then get bored of the whole idea..." is also so spot on for me, and no doubt many others too. It made me laugh. It also makes me mourn a touch for all the things I over-thought and procrastinated over to the point of boredom and then left undone.
I would urge you to stick with it even if you find the services in your area have a long waiting list.
The second time around when my privately obtained d's would not do for my current GP as the prescribing process entailed shared care, I just 'parked' the matter until the appointment with the ADHD clinic was given. Then I 'parked all thoughts until nearer the appointment time.
Parking things is my strategy for coping when things can't go as fast as I'd like. It removes the frustration.
Also, after dx I realised I'd been devising strategies for managing living on a day to day basis.
Also, I don't know how true this will be for you and the others on here, I've always felt like an 'outsider', always on the periphery of things looking in. I did my own thing really until I was about fifteen when I made a conscious effort to closely watch my peers to see what they did, what made them 'normal'. That helped me to fit in better when I went to uni, as I'd developed a pretty convincing 'front'.
After diagnosis (dx) I think I allowed the real me with all my 'lovely' ADHD aspects to surface. I found I felt more at home with me and much less bothered about fitting in. So it reduced a self-imposed stress I'd been putting myself under.