(I'm so grateful this place exists... just rediscovered CEMB after a long time... particularly hard day!)
I've lived with depression a long time and I'm not sure if it got better or worse after I left Islam. I totally get the idea of the "Void" the OP referred to.
Islam provided me with a mythology to live my life by, to psychologically lean on and without that it became like "What's the point?". Since I left Islam in my early 20s I have tried to fill that void and struggled immensely (now 31).
I believe deeply that spirituality helps me to manage depression, however on a deeper level there is an element of belief needed that I am "worth saving" and life often feels like a roller coaster or a rapids that pulls me around far too often. Ramadan in particular is a difficult time because the extended family shifts gears and I have to distance myself to stay intact. I've consumed a lot of self help books and had to set a lot of boundaries but sometimes it feels like the work is never ending.
When I meditate (very rarely), read certain spiritual texts or just get away from people and immerse myself in nature I get moments of peace which make the striving in between worthwhile... it's like a glimpse that there is something deeper going on.
I have also tried to go back to Islam from time to time but I have now realised it damages my heart too much to even try and I have to protect my inner child which is what it's all about for me. I try to do whatever makes that kid happy, because i think he's wiser than I could ever be. Forgiveness of Allah and Muslims and all of the crazy shit that goes on daily in this world is also a good practice. I say all this stuff like I actually practice it regularly - I don't! I aspire to... I was so depressed today I have spent most of it lying down! But I cant deny i have seen progress in my life from the early days of post religious trauma (PRT - it's real!)... it's a process.... I am not giving up yet.
Your story is inspiring, and I'm glad that you have found a place like this helpful. Keep on going, my friend, we will conquer this demon yet.