They might look circumcised since the foreskin usually retracts upon erection, and all penises you see in porn are erect.
Do you mean you can't pull your foreskin down all the way?
If so, your foreskin is too tight. But don't worry as 9 times out of 10 this problem can be self-treated privately at home.
You need to do some stretching exercises, ideally in the bath/shower, every day for a few weeks. Follow the instructions on this website:
This website also has some more general advice: