Cant pull back foreskin at 13, I feel like the tip of my foreskin is glued shut

So is the opening just too small? YOu can stretch that by pulling it back as much as you can without hurting yourself when it's erect. Just keep pulling it back and holding it there as long as you feel like holding it. IF you can get two fingers inside the tip you can use them to stretch it. Doing it in the shower or bath makes it easier in the warm water. I started using my two little fingers then moved up to bigger fingers and eventually three and four fingers. If the inner skin is stuck to the glans you can try getting some warm water inside there to soak it and pull it back gently so you don't tear anything. You can also try getting a finger in there to help separate it.