I would consider MAOIs, unless you have so already. If you follow the guidelines for taking them, they are among the most effective anti-depressions for MDD and TRD. If you do a search in any of the drug review sections on drug-related websites, you’ll get a sense of how many have benefitted. The only remission I ever had, albeit for only for five days, was when I took Parnate. I have taken several others in the MAOI class since with no effect, but I am now taking Parnate again and slowly increasing the dosage. I am also taking 400 mg of lamotrigine. You might consider mindfulness and meditation if that’s up your alley. Eat well and exercise. With a MAOI, you may need to take a sleep aid since insomnia is a common side effect. Good luck and keep on swinging! Misery loves company.