Hello annmaria... As your lovely Signature quote says: "... one thing at a time, all things in succession."
There is a author I'm fond of named Parker J. Palmer. In his book:
A Hidden Wholeness- The Journey Toward an Undivided Life Palmer (who has also struggled with major depression in his life) wrote: "I don't know who coined the phase 'Every day in every way, I am getting better and better,' but he or she must have had a great fantasy life. In sixty years on earth, my pattern has never been onward and upward. It has always been up and down and back around. I follow the thread of true life faithfully for a while. Then I lose it and find myself back in the dark, where fear drives me to search for the thread again." (Pg. 90)
Your post, along with your Signature quote, reminded me of these lines. So I offer them here. Your post & your Signature quote, as well as these lines from Parker Palmer's book, mirror my own experience. Every time I think I've finally crawled out of the crater for the last time, I find myself unexpectedly sliding back in... I don't know how common it is. I suspect it is very common. It has certainly been my experience.
I send healing thoughts your way, with the hope that, even should you slide back temporarily, your trajectory will continue to be onwards & upwards...