Concentration and me are not friends either. I was given Concerta to try, and even though I am using it prn (my own decision really) I have seen the difference it makes in me. I need to chat with my pdoc about a permanent prescription.
I hear your frustrations. I never thought of myself as being any less than perfect, as not to be able to do my job. Then along comes a 'careless' mistake, and I crumble. But we need to just go easy on ourselves. Realise where we are not that strong, and give those areas special attention. And remember that no-one is perfect, and mistakes happen to all of us