Hi Steph,
I understand your dilemma.. But sometimes you have to take risks in life. I would say quitting a job is not bad as long as you have clear vision of what are your next steps and you take a calculated risk.. I mean you can find something part time while you work on your writing skills or find something in that field…

Follow your heart and passion.. I understand this because I believe in this. You are lucky atleast you know what your passion is.. I am still trying to find mine.

Hope it helps!