Wow 17 years, I don't even think the average user on this board is that old
This is kind of a weird situation to be in. Since you have been there for 17 years clearly they would understand if you wanted to have a meeting an discuss a potential raise & or payroll. As well as your title.
Also as ardcor said, are you sure you want to be with this company? Just seems like for someone who has been there so long you have it rough. Maybe you would do better off somewhere else?
And I know it's "not polite" to discuss salaries, but I'm a student in college and I make $5 less then you working for a small agency as a graphic designer. You should be making more than that. What did you get paid when you first started there?
As far as your title goes, from what you have stated it does sound like you should be technically an AD. Is this a large company though? How many ADs/CDs do you have?
If you don't mind, post the website for the company.