Unfortunately my diagnosis came at the very late age (40+) because whole life I thought it is just me being lazy and unfocused and seeking medical help / medication is the wrong answer to such problems - only to discover now that some of our brains are actually wired differently and it's not that we are being weak or unfocused but it's actually the wiring in our brain making us behave this way and you can freaking see this on an MRI too.
If you can't get an evaluation at least try to read this book called driven to distraction. One other book which I also read again and again is 'Finish' by Jon acuff. Has many useful tips which anyone can use.