First of all, good luck to you Rusty. I hope you're able to get yourself straightened out.
And I agree with samUwell. Functional anything (addict, alcoholic, mentally ill) just means you are able to function in society at a certain minimum level. Keeping a job, paying bills, maintaining relationships, grooming, etc. It doesn't mean you aren't an alcoholic or are less of an alcoholic or whatever.
Look at it this way: some of you basement dwellers don't have any of these issues but are barely what one would call functional...