You don't need to go back to school, what you learned is still there. What we learned in school are only tools just like the pencils we draw with. Use those tools how you would like to use them. If you get tied down to the tools having to be used one way then you will be confining yourself. Once you have moved passed that the making art will come natural. I also just want to encourage you to move forward and to not define yourself by your failures and even accomplishments. We are so much more. I've learned that if we rely on how we match up against others in life will always be miserable and chasing after things that don't really mater. I found that my relationship with my Lord and savior Jesus, family and others is what really maters.