As an aside, as of the DSM-V, ADD is no longer used. It’s been combined with ADHD, which has split into 3 subtypes, which are inattentive (basically what used to be ADD,) impulsive (basically what used to be ADHD,) and Combined, which has some combination of traits from both.

I’ve heard, but not confirmed, that depression is a comorbidity among 80% of people with ADHD.

They neuropsychological testing with reaction times and very granular memory tests was quite interesting. If you get the chance to have someone deem it medically necessary, I recommend doing so.

Your description does sound like ADHD to me but even a diagnosis and treatment is only one part of what you’ll need. In addition to a therapist I think you really need a mentor to help you navigate the professional side of things. There are lots of shapes that can take but I would definitely prioritize it; if a lot of your stress and unhappiness is due to work there is a limit to what most types of traditional therapy can help with.