Ok, take all this with a grain of salt, but after 9 years working in advertising as a designer I hope I can speak to this topic at least a little bit.
First off, don't quit your job to go back to school... at least not yet.
Secondly, go read
Mike Monteiro's Design is a job. The eBook is $9 and it will give a real world look at what it's like working in the "creative" field. Spoiler, it's a ton of work, most of it not being very "creative" at all.
Aside from the advice in Mike's book it's important to know two things:
- Making a living in Graphic Design is hard.
- It is a very, very competative field.
Currently schools like ACAD are pumping out more grads than the industry can support, that's just a fact. I work in an agency and we get more resumes/applicants than we can read. So unless you plan on running your own business don't count on going to school and then immediately into the work force.
A more realistic path is to get the training you can while working your current job and working freelance projects on the side, with the eventual goal of quitting your current job to focus on your freelance work.
But the "leave the workforce to go to art school and then enter the design industry" is absolutely not a path I would recommend. Perhaps some other CP users in the industry can provide there own insight here, but truth be told most of the other designers I know are also business owners.