I don't know if this helps, but when I was learning about writing resumes, I remember hearing that if there is a large gap in your work history and there's no answer for it, they will assume that you were in jail.
If it's true that that's what they're concerned about, it ought to be OK to tell the truth: "I had trouble finding work" or "I needed to take some time off after school to decide on a direction to take" or something like that. Because that would allay any fears about you being in jail.