I don't like the "definitely an alcoholic" part of that test--personally, I could imagine many people who are situationally drinking to excess who might answer more than three questions with a "yes". BUT, at the very least three "yes" answers would seem to indicate a high probability.
I tend to think of alcoholics mostly as people who have (a) the obsession (even when not drinking, they are thinking about it or wishing they were doing it or actively looking forward to it) and (b) the absence or malfunction of the "stop" signal that most normal drinkers get when they are having too much. And, really, each person has to decide for him/herself whether that's true for them.
It is progressive, though. I started out looking forward with excessive anticipation to my twice-a-week after-work get togethers with my coworkers. One guy always bought my drinks, and I used to drink as much free booze as I could, while I could. Eventually, it evolved to my drinking every single day after work from the time I got home until I passed out or was on the verge. Everyone has their own pattern, and you can't tell just from the quantity or even from the pattern, especially early on. If it gets worse over time and you feel about booze the way alcoholics do, then you are one.