It took courage to be honest about what you are going through, especially when it feels like you cannot talk to anyone about it. Feeling trapped, foggy, and stuck in a cycle you cannot break on your own is a heavy burden, and God sees where you are.
What you are describing is not just a bad habit. Scripture describes three basic ways temptation comes, through the desires of the body, through what our eyes crave, and through pride. When those desires are fed outside of God's design, they do not stay small. Many men have found that pornography takes hold like a drug. It starts with a small sample or a curious look, and then it grows into something that feels like a captor. The reason it feels so powerful is that feeding the flesh never satisfies it. It only makes it demand more, and it leaves the mind polluted and the heart empty. The Bible warns that whatever a person sows, that is what will be harvested, and sowing to please the flesh harvests confusion and corruption, while sowing to the Spirit leads to life and peace. The world and its cravings are passing away, but the one who does the will of God remains.
That is why the brain fog you feel is real. When the mind is constantly filled with sexual images, it becomes clouded and weighed down. It is not just in your head, it is the result of what has been sown into your mind. Healing for your mind is possible, and it does not have to wait until a certain date on the calendar to begin. But healing rarely comes just by counting days or white knuckling to a milestone. It comes by changing what you are feeding your mind and by walking in a new direction with God's help.
Your question about stepping away from your phone shows good wisdom. If the phone is the open door for temptation, it is right to close that door. Jesus taught to deal radically with whatever causes us to stumble, and removing easy access is part of denying the flesh and choosing to walk by the Spirit instead. A filter, keeping the phone out of private spaces, and having less unstructured time alone with it are practical ways to starve the craving rather than feed it.
Counting to day 90 in November can be a helpful goal, but freedom is more than reaching a number. The deeper need is for your mind to be washed and renewed. That happens as you bring this into the light before God and before another trusted, mature Christian man who can walk with you and hold you accountable. Confession breaks isolation, and God promises that when we confess our sins He is faithful to forgive us through Jesus Christ and to cleanse us. Then, day by day, replace what you have been watching with what is pure. Let the Word of God wash your thoughts, pray honestly when temptation comes, and ask the Holy Spirit to give you strength to choose a different path. Learn to recognize the moment temptation first appears and turn away immediately rather than entertaining it.
You do not have to stay alone in this struggle. God is able to set you free from what now feels like a vice grip, to clear your mind as it is renewed, and to give you a love for what is pure. It will take time and consistent choices, and the fog will not lift in one moment, but many have found that as they consistently turn from feeding the flesh and begin feeding the Spirit, clarity, peace, and strength do return, often well before a distant milestone.
I am praying for you, that the Lord will deliver you from this hold, wash your mind with His Word, and help you walk by His Spirit so you do not fulfill the cravings of the flesh. If you do not have someone safe to talk to, please seek out a faithful pastor or counselor soon. You do not have to carry this alone, and God is ready to help you walk in freedom one day at a time.