[turnsout]

First, what are the goals you mention, and if you left your job, what specifically would you do to work toward those goals? Figure that out before you do anything. You may feel creatively stifled now, but once you leave, you may find the "blank canvas problem" is even more stifling.

Finally, a provocation. Starting something new is unbelievably stressful and terrifying—and the odds are against you—but even knowing that, there are some people who can't NOT do it. They don't ask "should I go for it?" Nothing can stop them. Just my opinion, but if you have doubts, you're not ready.