Welcome, MTB! I am new here as well, just been here a few days.
I can relate very much to what you have been saying. My primary addiction is sexual addiction, which may sound very different than alcoholism to some people, but it is not.
I have been sober for about 13 days, but once was able to rack up one or two years of sobriety. Then my addict told me that I had worked hard and so I "deserved" a little fun. My undoing was rationalizing my way into acting out. I wanted my have my cake and eat it too. I wanted to be sober and yet push the lines enough that I could "enjoy" myself. So I can relate very much to your wine testing -- I did the equivalent with explicit sexual material -- rationalizing a certain behavior and then pushing the lines as far as they would go. All this happened without me ever planning it out conciously. It is that baffling part of our addiction that has our addict always trying to find a way to make us lose our sobriety.
Once more I kept convincing myself that I could be "moderate" when I acted out. But it never happened. I could never control myself. Never.
I kept "chipping away" at my sobriety until I hit rock bottom. Then and only then were my eyes opened and I realized that I hadn't been sober for quite some time. I thought I was "technically" sober, but my sobriety was actually a confusing mess of rationalizations, lies, and half-measures. When I hit rock bottom, I actually felt some relief -- I no longer had to lead a double life, I no longer had to lie to people, and I no longer had to make excuses. It gave me a chance to begin again.
Thanks to great support from my fellow addicts (groups, on-line meetings, and this forum), I feel as if I can truly live my sobriety in the here and now, the present moment. I feel a great deal of freedom.
I hope these observations helped a bit. As I said, I am very new here, like you. I feel like a baby learning how to walk for the first time. I hope that sharing my experience helped in some way.
Welcome!
Chris