My question to you is simply this: is what you are doing now working, are you staying sober, staying stopped, and leading a purposeful life? If you are, then great! However, if what you are doing is not working, then why not try working the steps and join an SA meeting? What have you got to lose? We have it on good authority that the 12 steps are not contrary to Judaism; quite the opposite is true, the 12-Steps teach us the fundamentals of religion all over again, in a way that can often penetrate the hardest hearts.
In my experience, long before I came to SA, I went to speak to Rabbonim and Mashgichim, and they all sympathized with me, but none of them gave me the answer like the 12 steps did. If the answer was so simple as to learn more mussar or to daven harder, why did they not tell me this? The answer to me is, that most Rabbonim are way out of their depths with mental issues like addiction, they do not understand the phenomenon. And why should I expect them to understand it? Perhaps if one of them has had the occasional urge to look at porn, etc... the answer for them was always to be mechazaik themselves with mussar, etc.
Nowadays, we do not have the capacity of the previous generations to look into the Torah and derive the practical solutions for the world's problems. I am sure beyond a shadow of a doubt that there is a cure for cancer contained within the Torah, but which Rav would be so foolish to advise someone suffering from cancer, r'l, to immerse himself in the Torah to find the solution? He has to see a Doctor and start a treatment of chemotherapy. Lust addiction is a spiritual cancer of the soul that at any given moment is only getting progressively worse, as we try and maintain the highs. The 12 steps are a spiritual chemotherapy. For me (I speak for myself only), learning mussar in isolation would not work, I need the physical interaction of going to meetings, speaking with my sponsor, making and receiving calls during times of distress, and working the 12 steps.
Therefore, if you are still struggling with this insidious addiction, perhaps you should try joining a meeting and asking for help. You may be pleasantly surprised. For me, working the steps has given me a new foundation for my Yiddishkeit; it is helping me to be a true Eved Hashem. For me, it's not a question of "Torah vs. the 12-Steps," Torah is the 12 steps.
And the fact that it was originated by Non-Jews? I will leave that up to Hashem to worry about. There are so many inventions out there that were invented by the Non-Jews that we use to help us in our Yiddishkeit, let this join the ranks!