The way I was diagnosed was I went into a psychiatrist and said, "I think I have ADD." He asked me a few questions from a "Do you have ADD?" brochure he had on his desk and then said, "There's no sure way to diagnose ADD. If you think you have it, then you probably do." Then he put me on adderall and changed my life!
So my answer to you is, if you think you have it, then you probably do!
Good luck at your appointment!