As a former memeber used to say:
If you are an alcoholic, and drinking is causing you problems in your life, you'd better quit drinking.
If you are not an alcoholic, and drinking is causing you problems in your life, you'd better quit drinking.
In other words, the label doesn't matter. It's what the behavior is doing (and has the potential to do) to your life. Could you drink in moderation again? One never knows without an experiment. The odds are very high that you would become re-addicted quickly and eventually move more towards levels like your brother's, though, although that isn't a 100% given. The fact that you would even want to run that experiment, knowing the full risk involved if you are wrong and cannot in fact drink moderately, speaks volumes about whether you are truly addicted.
The addicted part of you is working you like a fiddle right now with all this circular talk. People without that addicted part would have long since walked away from a behavior that has caused them the problems you describe. Think about it.
Many of us don't even use the word "alcoholic" and don't believe in the "ism" of substance addiction. You can quit and be happily abstinent without calling yourself any kind of label.