I was eventually diagnosed at 60, and it was such a relief to realise I wasn't thick, lazy or just plain crazy. It explained so much about my life, why I'd behaved in certain ways etc.
My DBro was diagnosed privately, and immediately called me to say on the basis of what he'd learned he thought I should be tested. I did the on line tests, scored quite highly, went to my GP who asked me to do more tests - just a simple questionnaire with all the time, a lot, sometimes, rarely and never answers. On the basis of this, he referred me for formal diagnosis.
My health authority outsource this to a highly respected private company (who happened to be the same one my brother had gone through), and I had my diagnosis appointment within a couple of months - we did this on line in a video call. Turns out I score very high in hyperactivity, and top the scale for attention deficit.
Distractability is a big factor for me and inability to focus. My brain spends half it's time on a hamster wheel spinning & spinning, and I fall down rabbit holes easily. Pre-diagnosis I would describe myself as a "butterfly Tigger", bouncing from thing to thing at an incredibly rapid rate. I recognise the house thing, and the inside of my car is the same. Talking is a big issue with me, I plain talk too much.
I started on meds a few weeks ago, and the difference it has made is fabulous. I can focus when I need on tasks both work and house related, which in turn has affected my mental health as I no longer beat myself up all the time because I haven't accomplished anything. In my case we thought at first it may be affecting my blood pressure, but that turned out to be the job I was doing and when I left there my BP went back to normal.
One thing I learned to do very early on in my life was plan everything to death, probably helped by working in project management. Everything has to be planned and diarised; I even diarise regular tasks like weekly reports, including scheduling the time to do the work rather than just the deadline.
I've also realised that I am much better off in a job that doesn't have too many interruptions that lead to a complete switch in subjects or thought processes e.g. if I'm working on one thing, half a dozen calls in an hour all relating to completely different things will throw me right off track. This is exacerbated when you need to urgently react to the calls & not put them back until after you've finished the original task.