Im 15. Yesterday my uncircumsized foreskin retracted past my head for the first time. I managed to get it back over, with difficulty. Now my foreskin doesnt seem to cover my whole head and leaves abit showing. Now it feels really sensitive when it touches the inside of my pants.
Is this normal?
That sounds to me like it hasn't gone back on properly. I used to have exactly the same problems myself... it was extremely difficult to get it to retract, and even more difficult to get it back on again. And that's also exactly how it seemed and felt when it wasn't back on properly. Mine is also very sensitive to anything touching it directly.
I think what you need to do is pull it back again as far as you can get it, and then try to pull it back on over the head again, until it goes on properly and feels how it should. The way someone told me to do it, which seems to work for me, is to sort of place your finger and thumb each side of it, on the foreskin, just below the head. Then squeeze gently while pulling forwards, and that should pull the foreskin over the head. Doing it in the shower with the water running over it (or in the bath I guess) might also help it to move more easily.
As a last resort, I have also occasionally had to try to just grab the skin that was already over the head between my fingers, and pull on it, to try to pull it all the rest of the way up. But I wouldn't recommend trying that unless nothing else is working.