if you've tried that many meds without any lasting success, you may want to ask your shrink about ketamine. it works to break the cycle dramatically from one day to the next and has an extremely high success rate and low side effect profile in all studies done on it so far.
it's not fun. it is a powerful psychoactive drug and shouldn't be considered lightly, but it is one of the more promising treatments out there for treatment resistant depression.
look up the ketamine advocacy network to find a provider in your area and talk to your current doctor about it. do your own research and be well informed ahead of talking to your doctor, he likely won't be very experienced with ketamine.
--- below this point is a bit of a rant, but I hope it may be a helpful rant... ---
In my experience, therapy is useful for managing depression and preventing it from taking hold in your life. it has its role, but depression manifests physically as well and the physical aspects cannot be ignored. treat your physical depression and you may be able to make significant process with a therapist as well.
youve been on a long road with no great answers so far... but that doesn't mean no answers exist. depression is multifaceted and identifying and eliminating contributing factors is an essential part of the process.
depression is very personal in its nature, so nobody is likely going to be able to tell you why it's happening... but i can share what my contributing factors were in order to hopefully spark some ideas in you. no single thing was "the answer" and these are only the non-traditional aspects. traditional medicine for depression kinda sucks, but I think you already know that.
-undiagnosed sleep apnea -melatonin over metabolized (I burn through melatonin very quickly and my naturally produced melatonin wasn't enough to correct any sleep irregularity. I had to take 20mg (10x normal dose) for a month to establish a normal sleep schedule.) this was discovered via a liver enzyme genetics test, ordered by my shrink. -stressful work with irregular hours -zinc supplementation -anhedonia - the trap... i think of it in terms of a basic reward mechanism to reinforce difficult behavior. if you are unable to be rewarded emotionally (satisfaction, joy etc) for doing something, you are unlikely to keep doing difficult things. brought to its extremes, this is not leaving the house... not taking a shower... not doing the laundry... eating junk because it's easy... etc -escapism via smoking or video games or isolation. these are both cause and effect of my depression. they're things that catch you in a loop. all you need to do is identify the behaviors and keep it in your mind that it's the pattern of behaviors that's bad, not you inherently. the loop presented as: feel depressed -> escape into something -> any time spent not escaping hurts again -> feel depressed. it looks stupid on paper, but i found that pattern sneeking into many aspects of my life. just keep an eye out for those kinds of patterns and identify them as unhealthy. the rest will happen naturally over time.
for me, ketamine was an invaluable tool in identifying and changing recurring patterns of unhealthy behavior that were very deeply ingrained. for the long-term depressed, having a few weeks feeling human can provide the essential perspective required for change that depression would otherwise deny you. I think of it as discovering that there was a world without constant self torment out there. it was a powerful motivator for change after many years of constant depression.
I'm sorry that I talked about myself so much... I hope some of what i shared will be helpful to you along the way back to health.
good luck and know you are not suffering alone.