I'm a creative writer with severe clinical depression. The concomitant lack of self-esteem, motivation, and energy makes it difficult to produce. Other than my empathy, I can only offer the advice I've been given: make your creativity a habit. Even if it feels terrible, even if you look at the material you wrote the day before and cringe, just keep going.
I believe it was one of the Transcendentalists who felt he hadn't earned his dinner until he had at least written something that day. It's also helped me lately to read about Keats's concept of "Negative Capability."
The most important thing (and here I am hypocritical) is not to castigate yourself when you "fail." Self-flagellation feels "deserved," but it's really just a way to distract us further. It feels right because it's severe, and we think the hard thing is the right thing, but "severe" != "hard." The hard thing is to see ourselves as we are: not the best, not the worst, not lacking in creativity but not so perfected as to s&~* golden tomes or unassailable RPG content. You're at the choice point. Take care of yourself: sleep, eat, cry, whatever you need. But, when your needs are met, are you doing what you love to do?
Apologies if I am projecting my own flaws and struggles. This is just the stuff that gets me in front of my pen/keyboard; maybe there's something there to help you. Best of luck.