I'm in my mid-twenties, and once told a fellow drunk that I came in on a high bottom. He said, "A bottom is when your life circumstances worsen faster than you can lower your expectations." I think its possible for things to get infinitely worse, without it every seeming "bad enough" to force you to put down drugs/alcohol. You just lower your expectations every step of the way.
It seems that you and I are fortunate -- many people never recover from alcoholism. In my case, I cannot say that I "stopped myself" from drinking. I was stopped, by some power greater than my own will and reason. Every day I could come up with a good enough reason to get loaded. And then one day, the whole equation changed, and I knew that I needed help. I didn't "decide" that the equation should change, it simply did. And I can't count on that happening again.
I wish you all the best. The thoughts that you are describing, I have experienced them exactly as you say. I have toyed with them, believed them, talked about them, and tried to deny them. And, always, they eventually go away. Usually they are replaced with gratitude for whatever power kept me from picking up. I surely am grateful to be sober today.