I've been dealing with depression, or rather, a couple of months with productivity where I really work my ass off producing great stuff, then have an as long downtime where I just manage to get by. Any choir was tough to start doing and completing. After being diagnosed with both ADD and ASD.1 I also was diagnosed with Bipolar 3/4. Did not even know they existed but they trigger these hypomania periods. Turns out that hypomania is pretty good for working in IT and you can hide and get by the rest of the year. On the other hand, now that when I feel that the depression is completely gone, I discover that I'm entering a hypomaniac period. What a way to ruin all the fun. The awareness around it is quite low from where I'm from sadly. I wonder how well SAINT would affect.
You are not alone. I also have been going through something similar. I recently quit my job to work full time on my side project. I am financially secure for another year. I am very energetic for few days, I work my ass off and ship stuff. But after that I have these periods where I just can't do anything. It is hard to get out of bed. I feel like I am never going to make it with any of my projects.
I have been to a neurologists in the past multiple times and completed multiple courses of medicine. But those medicines I took had really bad side effects. And I realised the more I used them the more I was dependent on them for a normal mood. Also my brain felt foggy while working when I took them.
I do take time off after a few days of working but that alone does not help. This is a cycle. Planning on going out daily and exercising, eating more healthy and having a schedule with less screen time. Let us see how it goes. These things seem trivial, but I have never them for more than a month continuously. I want to give them a try this time like my life depends on it.
Writting about myself and what seems to have helped me.
Have been on medications for two years (getting off of them now), and in therapy for a year. Likewise, I had (or have) troubles with feeling stagnated/unmotivated after bursts of productivity and motivation.
The key insight was that creativity and productivity does not come without cost. I used to overwork myself and my body. After "feeding" the intellectual part of me, the other parts became "hungry".
The solution for me is to have breaks, even when I am in the state of flow while doing something productive, and use that energy to work on the dull activities that are required to keep me healthy - physically and psychologically. The stream of consciousness style of journaling helps me as well - it helps the root cause of my bad feelings show themselves, sometimes in a subtle way.
What you may want to have a look at is Active Imagination[1], it comes from Jungian analytical psychology. I find it really helpful.
The key here is "work my ass off". Even if you want to work, limit that part off and put that energy into training (like swimming e.g.). I know that sounds dull, but dull is better than not getting up from bed. If you are going to make it without the meds to stabilize, do limit the time you work in a manner that you don't fall in those cycles.
A well put metaphore I've heard is that you got a set of forks which you use daily. Make sure you don't run out of them. The problem is that it feels so great just using them all when you get a new clean batch after a couple of days of downtime..
Good for you that you are aiming for stability. Setting a structure and planning for mentally tough parts of the day (like social events) and never parting from that can make a total difference in life quality. It would for anyone obviously, but with living on some spectrum it's a life ingredient. Yeah, it's tough, and yes your life (as in with great life quality) depends on it.
Bipolar 2 here. I didn't get diagnosed until I was in my late 20s. I just thought I got carried away with things sometimes. I got on lamotragin a few years ago and I've been Even Steven since, but I do sometimes miss the productivity of the mania. Not worth the downs though.