Not to get all Zen like, but they say the journey of a million miles starts with the first step. as @StillWaiting says, do writing when you enjoy it and you never know if that time period expands a bit more once you exercised that part of your brain. I learnt something the other day, maybe it is relevant, maybe its not. I wanted to know why I don't laugh anymore, was it the depression and other things? There was some obscure academic paper that proposed the synaptic connections in our brain regarding laughter can deteriorate if we don't find ourselves in situations where we laugh. So basically we forget how to laugh
Perhaps maximise on opportunities to do things a bit more when you do have some clarity of thought. Sadly i know when I have clearer days I just think 'Lovely! A day off' but still do the same thing of sitting at home. You might be able to use the fruits of those times to act as a trophy to do more. Perhaps do something random! When I was younger (much much younger) my friends and I would do random trips. Go to an airport, get a ticket to anywhere and spend the weekend their. Ironically enough, it was the worst places we had the most fun in because the venues were so bad all you could do is laugh. you don't need an airport to do that, if you have a car or a bus ticket, its exactly the same. Its hard for us with depression to go out of our comfort zone or find the energy/motivation to do anything, but maybe give yourself the gift of doing something completely different. If you don't like it, well at least you know. I know you don't feel like this and my next statement might come over a bit 'its all about me', but I would rather be your age with more days ahead of me (potentially) and more options, then where I am which is the reverse. That statement wasn't meant to be a competition challenge on which of us is worse off, its just a point of view.
If I was 22 now, I'd probably go off to some farming commune a 1000 miles away from civilisation, phones, internet and all current affairs. Pick fruit and plant potatoes, build relationships with my fellow farm workers just to see if I was the problem or the world around me conspiring.
I truly hope you find you passion, but remember to find it, you must first go searching for it. Its rare that it lands on your lap. I hope you find it
Hoping you don't read that as if I was being preachy