We are in the same situation. It's been 4 years since my dx and I have been through all the meds too, really-with the exception of antidepressants b/c pdoc doesn't want me cycling. I have also been very hesitant to try Lithium, that is the only other one I have not tried. I am at that point where not only the depression is causing this feeling of hoplessness, but I feel that way in general due to the meds not working and meds-wise I do feel I'm out of options.
It's a scary feeling and I am going to be talking with my pdoc in great length about this at our next appt in three weeks. I think I am going to beg for the antidepressant because this episode of depression has gone on for months and I can't take it any more.
I don't know really what to tell you, except to say that you are not alone and I am sorry to hear that you are experiencing this barrier as well.
Take extra care of yourself, do something to help you relax and I will do the same after work today.