Obviously, this goes without saying, but please do what you need to; don't put yourself into a corner by anything said by anyone. I'm just giving my experience as i think it is a positive one.
I have enjoyed depression (quite severe is an understatement) for about 14 years now. I'm 26, so that's a little over half of my life which has been interesting. It came about from some abuse here and there, some neglect there, and a lot of desperation as i had no support structures.
Never used SSRIs or any anti-depressants, never got therapy; currently a smoker and a recovered alcoholic. Alcoholism was one of the most destructive and damaging things I have ever done, it is why i smoke as it's deeply damaged my body and mind, it took years from me, i feel twice as old as i am and there doesn't seem to be anything i can do other than try to smoke less and take better care of my body, though i feel both physical pain and emotional turbulence every day.
I currently, at this point in my life, realize that while I may not be able to ever be cured, but i can improve my condition, one day at a time. I think life is beautiful and I think that while my illness is crippling at times, i try to remember to hang onto what is beautiful. When i start spiraling i have trained myself to listen to music i find calming, to move myself outside (i'll often lay in the grass just breathing in the smells and looking into the sky, it helps when you distract yourself from the pain). I'm dedicated enough to it at this point that even if i can't get out of bed, i will crawl just to get that fresh air, to see the beauty around me.
Another thing i would encourage, i doubt it's a popular opinion but i do care, and this is what works for me. Stay away from pr0n if you view it; i find that when i stay away from it I can feel spasms of genuine happiness as it's almost like by not scheduling my daily, or every-other-day, dopamine rush... even WITHIN a week i will feel more energy to achieve that reward through making music or exercising.. or even just an embrace from someone i love. It all means so much more when i'm not scheduling that dopamine hit, it's like I HAVE TO DO SOMETHING! :) Anytime i slip back into it i find myself loosing ground. I'm just saying, if this is something you do, try it; you might find you feel better.
But most importantly, whether you listen or not, or try anything i'm suggesting; you need to remember that you are not alone, and even when you are at your lowest that you can imagine, you are never too far gone to reach out and ask for help. And don't push yourself past your means, the worst thing you can do is take anyone's advice and hurt yourself in the process, ease into something, don't go full hog, you know?
Another thing i noticed is that you said you find that nothing solves the problem permanently. I can say for me personally that i don't think i can solve it permanently, however i stopped fighting for perfection and just had to learn to try to improve how i think about things. Once i learned a healthy way to not just cope, but to actually live (not just survive) with it, it started to become more like background noise, even though it still affects me daily, it seems easier. I do more, a lot more than i ever imagined, but i'm always tired, though it's worth it.
It might sound a little strange, but as someone who has suffered from chronic depression since i was young, suicidal for the first 10 but now i'm (finally) safe, I've stopped treating it as something i have to "fix" and more like something i learn to treat in my own way.
I'm now an insomniac who works ridiculous hours (at a great job), i have a nice car, i love my music, and i guess has finally learned that even though it's not optimal, it's the best i can do with what i've been given. I think it's wonderful that you are still being a functional member of a team; try to appreciate those achievements, people appreciate your hard work.
There are still many days that i find myself not being able to get out of bed for hours, so i set the alarm to wake me up earlier. There are days i don't want to see people, so i work myself up to go see my friends. I've learned to ignore my own emotions to some extent and just push, but not TOO HARD. Know your limits, know what is "uncomfortable" vs. "destructive" to your mental health.
This is just me, that's just what works for me. I'm an expert in the depression experience, nothing else, and there are those around me who have better ideas i'm sure.
I hope something i said can be of some use. Best of luck to you.