If I may offer my humble advice, which you of course do not have to take, here is what has worked for me.
Many men struggle with viewing pornographic images on the internet. It is simply so easy and seemingly private that it is almost impossible not to give in. When I was your age over a decade ago, I thought that I would not struggle with such temptations if I was married and able to "have sex", thinking somehow that marriage was a safe haven against the temptation. Unfortunately, that is not true, and marriage is not a cure-all for these things.
So what can you do? Should you despair and give up hope? Of course not.
The first thing you have to do is be honest with yourself, and realize that no matter how much you do not want to sin in your heart, another part of you does
want to sin, and will in certain moments of weakness if you allow yourself to have the means to sin available. On this point a certain passage of Holy Scripture has become my motto:
And if your right hand causes you to sin, cut it off and throw it away. It is better for you to lose one part of your body than for your whole body to go into hell.
What does this passage mean? Should you mutilate yourself?
It means that we should cut off whatever things in our lives lead us into sin. You have to be honest and realize that when you refuse to repent of a sin, you are in danger of damnation. You should fear hell and the judgment of Christ enough to do what is necessary to remove the sin. In this case, the thing which is causing you to sin is your computer. So should you get rid of your computer? Well, this might become necessary at some point if other options do not work, but most likely not.
Once you are honest with yourself, be honest with someone else about your struggle. Your priest is a great first step, but he cannot micromanage your life. You need to talk to a close Christian friend, perhaps your Godfather, about your temptations, even just in a general way. Something like "I struggle not looking at all of the garbage on the internet."
Here is a program that you can download for free that lets you filter content out of your computer:http://www1.k9webprotection.com/
Install it, and then have someone come over to your house like your Godfather or someone else to keep you accountable. Go through the filtering options with them, and be totally honest. Cut off all the things that will be a temptation. There is no sense in only going halfway. There is no harm in being overly cautious. After the settings have been selected, and this next part is why you need the other person, have them select a password, and then do not let them tell you what it is.
Now, even in your times of weakness, your computer will simply block the access, and there is no way to override it without the password. So if you're close enough to your dad or someone you live with to have them do the password, then that will likely be more feasible then having someone come all the way over to your house for this reason. You'd likely have to explain to your parents why somebody from church was coming over anyway, so the awkward conversation might still occur regardless. If your parents are Christians, then more than judging you I would think that would appreciate your honesty and be glad to help you without being too intrusive.
All of that to say that this has worked for me. My wife knows the password, and I never will, simply because I cannot trust myself. All she knows is that the temptation is just too great for me without safeguards, no matter how much I love Christ or her, there are always times of weakness, often when we least expect them. She loves and respects me for my honest in this, and any good Christian will do the same for you.
Obviously doing this one simple thing will not remove every impulse for sexual sin or cut off access to material from other avenues, but it will take care of one primary source; a hand which causes the sin. May God forgive us all, and may you have strength against the enemy by the power of our Lord Jesus Christ.