If there is any way - any way - to access formal diagnosis for ADHD, do. Even if it means getting help to get through the paperwork hoops. (For US patients, Psychology today has a database that lets you search for specialists by specialty - here, ADHD - physical location, and insurance they take.)
You're describing basically a hallmark behavior for it (inability to direct focus) to a degree (as discussed in zine, $) that clinicians are likely to take very seriously. At a first appointment, in addition to whatever other prep you want to do... print a copy of this zine, and give it to them. As far as "the fine art of being taken seriously," this communicates very clearly the problem you are having and why it's dissatisfying to you.
EDIT: as far as the zine, rather than "I experience a rather strong emotional response to its message", high compliments on the formatting/art/etc