I used to wonder the same thing. My husband could go days, weeks, sometimes even months without drinking. I wondered so many times if I was the one that was wrong in thinking that he was an alcoholic. I checked every list there was that I could find listing symptoms, behaviour, etc. to find the answer. But what I finally learned and accepted is that regardless of what the label was (or wasn't), his drinking was causing problems.
May you somehow find peace of mind.