Ketamine treatment for depression is still being studied so you may have trouble finding a doctor that will take you in. You state you have had depression for many years, is this well documented? What I mean is do you have a psychologist or a therapist that you have a history with? I think it will be extremely hard to get a slot in a ketamine treatment place without a long documented history of depression coupled with attempts to be treated with more routine procedures. I may be wrong but it just seems like you would need that to be a participant, as in they wont just take someone off the street who claims to be sad.
As far as the Valdoxan that Mysterie posted, that is fascinating I have never heard of that class of antidepressants. I am excited that they are trying new things in a feild that really hasnt seen much development since SSRIs were created. Thanks for posting that I cant wait to absorb all that I can on it and become even more powerful!
But I digress, I think you could get away with making your own infusions if you do a lot of research. The goal is to not get "high" but to get the mood stabilizing effect that ketamine has. Even I experience this with my recreational dosage, for example if I am at a festival and I feel like i need to do something and I have the restless, this isnt going how i thought it would, first night jitters or whatever, Ketamine removes that and puts contentment in its place. And that last bit is what you want to achieve and the effect lasts way longer then the drug, at least thats the claim. My guess is it is a replacement for electroshock as you need multiple sessions every month for that too.
I say try other things first, there is no reason to jump straight to a new controversial and essentially untested treatment until you have tried all others. And you can take this time to read all that you can. I hope this helped.