Um, you're 21, according to your profille? I just don't know enough about art to be sure how much money you could make that way or how much 'school' you'd need! Maybe, if you do design as a main job, for now, you can do your other art as a hobby & see how it goes?
Can't really advise about the 'never being 100% satisfied with your work', apart from you're a perfectionist & art isn't too good at subjecting itself to critical scrutiny. Artists tend to be their own worst critics (from happening to read book blurbs & so on)!