Welcome to SR Michael, some folks just drink to much and when they decide to just quit drinking, they simply quit. Perhaps you are amoung those folks, then there are alcoholics which come in many varities, the common denominator is alcoholics when they decide to moderate thier drinking may for a little while, but some how seem to wind up drinking just as much as they did before, then they will try to quit totally and may have some success or none to speak of at all, but they find that they always seem to wind up drinking again.
Here is one of many test that are pretty good as far as indicating if one is an alcoholic or not
Alcoholics Anonymous : Is A.A. For You?
The key to accurate results with any of these test is to be BRUTALLY honest when taking them.
If you find that you are an alcoholic hang around, ask questions, seek out a long term recovery program because if one is an alcoholic today, they will still be an alcoholic 20 years from now even if they reamin without drink the whole time.