Maybe the problem is not your addiction to porn. Maybe the problem is you are trying to "fight" the addiction.
I was addicted to pornography up to my early 20s. I became disenchanted with it when I later realised that the content of porn has very little to do with reality, that it's little more than fantasy. Now I watch pornography perhaps a couple of hours a month. I'm sure my meditation practice and dhamma study had something to do with it, but I didn't try to fight the addiction. The addiction just burned itself out. Now I find that most of the time, porn even turns me off.
You said you're trying to overcome an addiction, but I am not sure if there's anything that needs to be overcome. Just how bad is your addiction to porn? Is it so bad that you lose sleep at night watching porn? Is it a serious obstacle in your daily life? Do you, like, skip school or not go to work, just so that you can stay home and watch porn all day? Do you often feel the urge to commit sexual offences? Is it affecting your relationships with your family and loved ones? Are you sure you're not overreacting to your own addiction?
You cannot "meditate away" an addiction by force of will. If you sit down and meditate with the express aim of getting rid of your addiction, either the mind rebels against being controlled and you get nowhere, or you end up convincing yourself to feel a placebo, false sense of progress. Try something different. I am thinking what Ajahn Chah would say if he were reading this. Instead of restraining your mind to stay away from porn, try forcing it in the opposite direction. The next time you feel a craving for porn, put a clock on your desk, load up all your favourite porn sites and challenge yourself to watch porn for longer than usual! See if you can watch it for an hour, two hours, or three hours longer! See if you can break your own record for number of hours of porn watched in a day. See if you can break your own record for number of orgasms in a day.
Eventually the mind will get bored and it will want to do something else. But don't go away yet. Stop, and reflect for a moment. That is the time to ask yourself the crucial question: why am I getting bored of this now? Why don't I want to watch any more porn now??
quidquid Latine dictum sit altum videtur
(Anything in Latin sounds profound.)