Hi OP. You've spent a lot of time considering this and although you're almost certain of your ADHD diagnosis, you are looking for a medical professional to confirm this back to you, to help validate your experience, and hopefully move forwards with greater personal insight, and perhaps some practical, possibly medicinal, support.
This is completely understandable, and to me it sounds as if you need to stop doing the online quizzes and get on with pursuing the professional assessment that will ultimately confirm or deny an ADHD diagnosis.
I would suggest you contact your GP in the first instance, to request a face to face consultation.
Then, while you're waiting for a response, write an email/letter to the GP, both outlining, and detailing, your concerns. Definitely list your symptoms, along with how these affect your daily life. Summarise what you'd like to happen next, i.e. an assessment.
Then, depending on whether you are given a face to face appointment, or requested to write to the doctor directly, you have something ready to either use as a reminder in your face to face meeting, or send via email.
It's likely that if the GP agrees to referring you for an assessment, the wait time is likely to be many months, although not always. You may be lucky and be seen more quickly, and the process is likely to be multi-faceted and multi-staged.That said, I only have experience of child services, and maybe it's different for adults. In our case though, we were initially sent questionnaires to complete (as were the school and other relevant settings), then we were seen by a nurse for a triage appointment, and then finally another appointment with a consultant psychiatrist.
I wish you the best OP, although do be prepared for the strange mix of relief, sadness, grief and loss that comes with such a diagnosis.
And remember, most of us, ADHD or not, never reach our full potential, so try not to feel too bad about that. Life just gets in the way!