Chances are you'll want to try for six months just to see where you are in all of this. The short answer, as you noted, is you probably should plan on quitting for good.
One thing you may want to read up on--I did not know about this until my last quit (successfully)--Post Acute Withdrawal Syndrome. It's a collection of symptoms that can pop up weeks or months after after you quit, sometimes you'll be feeling pretty good then WHAM! you start feeling poorly again, with no obvious reason. Some people think this may be the thing that sends many people back to the bottle--they feel badly and they don't know why.
Knowledge is power. Good luck!
PS. Sober since Feb 1st, battled PAWS since April 11th, still sober, symptoms diminishing.