What a gripping tale of tenacity, triumphs and hope is your post...I had to copy it on a word file to go thru meticulously and repeatedly to understand properly get back to you.

So, yes, first congratulations on having "lot of [excess] weight" and "feeling healthy."
But unfortunately you "still feel depressed and null most days." You have morning paralysis and invasive thoughts which leave you exhausted and feel empty most days at the end.

And YET you want to try DBT, a version of CBT, which I have used when I had my severe anxiety attack to understand the Source of my anxiety: Realizing that my research, analysis and insights along the way that I had turned into a manuscript of over a hundred thousand word doc is what nobody seems interested.
I'd to accept this reality,,,and Move On with life what it still had for me to RELISH.

During my many years of serious interest to non-medical understanding of mental health One thing that I found as a core element of living a healthy enjoyable life is to have a defined Purpose. A purpose that think if I followed in your life and died or become severely compromised, say, tomorrow, I could still say, " you know, too bad, but at least I busied myself what made sense to ME. And yes it need to be a purpose that I'd have had deliberated long and hard with some benefit to people other than me. So Not being famous, rich, strongest, or very popular, or even healthiest. The last one, if you are wondering, is because I need a purpose that will carve and shape my 24 hours. This is how it works for me--Before going to bed, I already have what I wish to do mt next day...and week and months. Your "hope" to be "alive" in every sense is there, thankfully, This idea of purpose is fleshed out in Prof Patrick Hill of Wash State Univ at St. Louis. There's also at least one book that deals with it.

I do wish you get the life you want. Happy to answer any questions. Good luck my fellow human!