I know exactly how you feel. I used to feel like that a lot. Tried meds, they seem to cheer me up a little bit and then eventually stop working, and I get lots of unpleasant side effects. For some people though the difference is dramatic. I think different people are helped better by different approaches or a combination.

Now I am trying to make some significant and positive life changes at the moment, get my life to the next level, those same thoughts and feelings crop up again periodically out of the blue with some force.

Have you considered posting your work for critiques and feedback on an arts site? I use deviantArt, the community there is mostly warm and friendly.