I think I have adult ADHD-PI. How important is the diagnosis?

I'm 32 years, and for all of my life, I knew something was..off. I've often battled despression, but anti-depessants never work on me. After talking to my GP, and finding out about this forum, I think I have ADHD-PI.

When I was laid off in July, I wanted to fix this because I felt it's holding me back. So I spoke to my GP about this, and obviously the next step is to see a psychicist through my network right? The problem is that I have shitty insurance: Molina Healthcare via Covered California. (My previous job, I was a freelancer so I didn't get benefits.) Literally, all of the psychiatrists they had listed, were either no longer associated with them, out of practice, or not taking any new patients. I've called Molina many a times, and they've tried to help but it always end up going no where. And my GP's has some referrals, and again, Molina is not in their plan.

After telling my GP about this a month later (July), he has agreed to prescribe me a low dosage of Adderall, and my God, has it been working. It's only 10mg, but I'm seeing improvements, and I feel normal for once. My brain feels alive and functioning. I feel good about myself, and I don't think it's the buzz (which I don't really feel).

So my question is: Where do I go from here? And how important is the diagnosis from a specialist, if I can get medication from my GP? I'm 90% convinced I have it, and yes, it's important to get it official. But I'm running out of legit options.

Also, I'm not familiar with medical records. Are they consistent, like with background check or credit score? I've been to so many different doctors in my life time, so do they have access to the some files? I'm just asking about the legitimacy of any diagnosis, and how 'official' it is.