I'm pretty sure bigger guys tend to have foreskins to fit their penis size, based on how the penis grows. It's tough to explain, but I'm 90% certain.
It sounds to me like you have a long foreskin that covers your head when erect. You have a bell-end; it's just under your foreskin. A small minority of uncircumcised guys don't have foreskins that can retract. If you want to retract but can't, there are easy ways to fix that. I'd first try stretching your foreskin forward
. If you don't see progress, read this:
EDIT: Argh! Stupid spam rule. Replace (dot) with a dot; sorry.
But if you can pull back your foreskin, ignore that last paragraph.
Many (most?) guys have foreskins that don't cover their entire glans (heads) when erect. There's nothing wrong with either, but that's the explanation of why you look different.
Hope that helps!