I have worked in environments where as the day wore on, my performance plummeted.

After a lot of investigation, I suspect that air quality, lighting, ergonomics can have adverse effects. Only recently I read an article that said that in a room with several persons and poor ventilation the CO2 levels reach levels which are known to impair brain and other neurological functions.

That is, I suspect that your depression is the symptom of a bad environment and not the root cause of your problems.

I can sympathize with what you're going through OP. I have similar struggles myself (primarily with severe anxiety) and wouldn't wish most of what I have had to go through on my worst enemy.

I do have one comment though:

You mention stability in your goals, and how you want to find stability. What is stability to you? I've struggled for years with trying to find stability but it often just leads me back to thinking that there really is no such thing. You just never know what is going to happen in life. Finding a job and having stable employment are hard, and will likely only get harder as we age. Relationships have ups and downs, and their downs can be incredibly challenging to navigate. Most of us (at least in Europe) don't have the luxury of building wealth to escape the 9-5 grind. We simply need to work (and stay employable) until we have the ability to retire. I don't know how things work in your country, but here in Sweden I can't even start to collect my state pension until I turn 69. I need to find a way to remain employable until I am 69, or amass enough wealth to not need to worry about paying my bills if I don't have stable employment.

I could go on and on but honestly I think stability is a myth. Life is inherently unstable. But we human beings are also incredibly resiliant.

Take care of yourself. I wish you all the best OP.