I thought I wasn't an alcoholic for a long time because I didn't drink every day and I hadn't gotten into any serious trouble. A little voice in my head was telling me I abused alcohol, and should probably think about quitting, but I didn't listen. I was only doing the same thing most of my friends did. We were having fun! I was like you - I could go days without drinking, but when I did, there was no off switch. But over time, the consequences started to pile up. I won't go into detail - I'll just say that it got really bad. By the time it got really bad, I knew I was an alcoholic. I could still go days without drinking, but when I did, all bets were off. My self-esteem had sunk to an all-time low. I hated myself and my life. When I started becoming suicidal, I knew something had to change. I put myself in outpatient treatment, started going to AA, and admitted my problem to family and friends. I've been sober since December 2014.
That long-winded story does have a point - If you are here, posting, and worried about your drinking, you have a drinking problem. You might not be ready to call yourself an alcoholic - and you don't have to. Just read some stories here to see what is probably in store for you if you continue down the road you are on. You don't have to hit a bottom like mine before you decide to quit. But you have to really want to. Once you admit to yourself, and ACCEPT the fact that you have a problem, you can begin the process of making a better life for yourself.