Great question. Given the list of medications you have tried (which address both serotonin and norepinepherine issues), it seems reasonable to rule out depression as the guiding force in your struggles at work (and personally). I do tend to wonder if they did work, at least partially (given that you mentioned you are experiencing depression "again," which tells me it has been on and off).
But to your first question... it is (of course) impossible to diagnose over the internet, but the symptoms you describe do smack of adult ADD. Too, none of the meds you have tried address the neurotransmitter implicated in ADD, which is dopamine.
However, the symptoms you listed can also be the result of depression, which is probably why your doc tried you on all of the anti-depressants. It is a bit of a chicken-and-egg because I would imagine that your depression is driven and deepened by the stress over feeling as though you could lose your job again.
One thing I would look at if I was your therapist is a family history of symptoms that seem to mimic ADD or ADHD. Another possibility is if there is substance abuse in your history, as adult males (in particular) are prone to self-medicating the stress/depression brought on by the disorder.
So here is my advice: Talk to your doc about going on a medication trial of an ADD medication. I recommend you stay away from Strattera, as that med addresses norepinepherine, and that has already been tried. The upside of a trial of stimulant medications is that they are in and out of the body rather quickly because they are very water soluble, so if the pills do not help, or in fact make you worse, you simply stop taking them and they will clear your system by the next day or so (unlike the meds you have been on, which require time to build up AND time to taper out). You will know within the first couple/three days if the pills are going to help you or not.
But if the pills do not work, I would recommend talk therapy to help arrest and change some of the ways you talk to yourself (i.e., the elevator music constantly playing in the background of your mind) in hopes of altering the course of the current or future bouts of depression. But try the medication first - I think you will find that it helps.
If you are satisfied with the response, please hit "Accept." That is the only way I can receive credit for my answer. Thanks-