No. It is not too late. It is never too late.
Pornography is a very addictive stronghold. It is strong! But God is stronger and God forgives. "If we confess our sins to Him, He is faithful and just to forgive us and to cleanse us from every wrong." (1 John 1:9 NLT) Also, God will work with those who have a tender heart towards Him, and it sounds like you do.
1 Corinthians 10:13 NLT says " But remember that the temptations that come into your life are no different from what others experience. And God is faithful. He will keep the temptation from becoming so strong that you can't stand up against it. When you are tempted, He will show you a way out so you will not give into it." The King James Version calls this a "way of escape."
It often feels like the temptation is too strong. I know. But please begin to ask God to show you "the way of escape" when the strong temptation does come.
Try to figure out when and why you are most susceptible. Put plans in place ahead of time of how to avoid those situations, if possible, and of how to react and of what to do when they can not be avoided and temptation comes.
Also, please try to find someone who is an adult that is a strong and mature Christian that you can trust and that you can confide in. Let them know of your struggle, so that they may be able to help you when you are feeling powerless.
Don't beat yourself up when you fail. Go to God again. You can go to God as many times as you need. If you are humble and sincere, He will work with you. Please remember He is patient, and gentle, and kind. He is not there to condemn you, but to help lift you up. Look how patient Jesus was with Peter and the rest of the disciples. He will work with you.
When you fail, confess to God, get up, and start over again. Remember, He cleanses us.
Celebrate your successes as well!!!
This is not everything, but it is some things you can do.
I will pray that God sends someone into your life that you can trust and talk to. I will pray that you never give up, because God will never give up on you.
He cleanses and cleanses and cleanses, again. He helps us to change (maybe slowly...but surely) as we continually look unto Him.
Paul did a lot of things that he was ashamed of, but God cleansed him. And he wrote "No, dear brothers and sisters, I am still not all I should be, but I am focusing all my energies on this one thing: Forgetting the past and looking forward to what lies ahead." (Philippians 3:13 NLT)
You are precious in the sight of God. He loves you. He will work with you. He will strengthen you. He will keep on cleansing you. He will send people to help you. He will send ways of escape.
It is a strong battle, but God is on your side!!! He is always near and ready to help!