But I only lose control sometimes!

Diseases have symptoms. Those symptoms are not permanently, universally present. Some people have back problems. Sometimes it hurts, sometimes it does not. Just because, on a particular day, it does not hurt, does not mean that the problem has gone away. If you have a chest infection, you will cough. But not constantly. Just because you go one hour without coughing does not mean you have no chest infection.

But if your back regularly hurts; if you are coughing a fair amount, there is definitely something wrong.

So, if you ever lose control when you drink, you have a problem, even if it's only some of the time. All of the times you didn't lose control are irrelevant.

What does it mean if you have this problem (in conjunction with the propensity to return to the first drink despite the consequences)?

It means you have alcoholism, which is a disease that is progressive, fatal, and incurable, and, what's more, has an invisible line marking the point of no return, and that line can occur at any point during the course of a person's alcoholic career. Ever seen someone in AA slip in their 20s and then fail to make it back into AA, for decades, as they slip further and further into alcoholism? I have.

This means that, if you've stopped, you had better stay stopped.

So enough already with the it didn't happen every time!