Take some of the questionnaires from more legitimate ADHD resource sites. Where I scored highly likely to be ADHD, my partner did not at all.
That being said, you could also undergo psychiatric assessment with a psychiatrist, but it may be a little expensive. I would recommend it if you can, because medication and appropriate psychotherapy can greatly improve quality of life.
Thanks for the encouragement. I've been put on performance for a while at work and despite my best efforts the situation isn't improving. I've only got a few more weeks before basically guaranteed termination.
I definitely did have a moment recently where I found a mistake in something I made a point to go through with a fine tooth comb when I did it, and I was so horribly disappointed in myself I wanted to cry and resign because I tried so damned hard, but I still screwed it up.
And you are right about gaining experience and starting afresh. I hope that as I go along I'll just gain more experience and be better at my job until I can work and meet expectations, like the average neurotypical person.