It took a relapse for me to realize that quitting was more than just a decision that I had to make (though an important part). The addiction wasn't going to just let me go.
It was more than quitting drinking. I had to recovery from alcoholism.
Perhaps you need to find a recovery program, some form of face-to-face support to get you through this. I won't mention any particular method, but something more structured than your current plan...whatever that it, which isn't working.