Well I am not sure how much help I can be as you do seem to have tried alot but as a fellow australian & this being a.N.Z.A.C. Day I must at least try!!
i too have been through the wringer with meds & drs of all types & I suspect that in my case it is more not prepared to put in the work then unable to get out of the hole!! If this is you too then all I can say is that we will both still be leading depressing unsatisfying lives 15 years from now unless we do act.
In that vien though I do have a couple of suggestions, a psych I know is very holistic & into natural cures so here is his advice - you need to choose what you feel a) might be of benefit (all potentially) & b) what you are willing to actually try for at least 6 months as natural therapies are not instant cures;
i) take a 30 - 60 minute walk around dawn as at this time (even if overcast) there's something in the rays of the sun which alters the brains chemistry to reduce strss/depression,
ii) natural meds eg, valerian, viatmin b, sam-e (200-400mg), dhea (25mg), 5htp (trypophan) - these last 2 you have to order from overseas as they're not sold here & dhea you need to find a dr who has government approval to get it,
iii) yoga - especially good if you do it with the meditation component which helps relax/destress you,
iv) cbt (cognitive behaviour therapy - only if you're willing to do the homework/exercises) available at some hospitals & universities (cheap/free),
v) consider what is lacking in your life (hobby, fun, study etc) & do something positive to fill the gap.
Hope this is of some help.