When I get an erection, the skin never seems to pull back

Ok, So this is really weird and I'm pretty sure it will be the first time you've ever heard of something like this. So all along I always thought my penis was different to other mens. I am not circumcised and still have the skin over my head, but that is the problem. When I get an erection. The skin never seems to pull back revieling my head or tip of my penis. I was so currious as to why, so when I was younger. I googled more about the male genitalia and only then realized that I wasn't circumcised until mid teenager. So the problem I have is. My skin never seems to pull back. I've been so big the one time. And inside I could see my head. And I pulled on my skin trying to get my head out of the skin, but it feels like I was going to rip my skin and bleed, because it was really getting sore. So I stopped. Now I am scared if I have sex oneday. That if my penis goes inside the vagina. That my skin won't pull back. And if it does. That it will only go so far until it becomes sore and unpleasant for me. And that would really be horrible for my wife. I really am so currious as to what is wrong with me. If there is something wrong with me at all! Or am I being stupid or what. In all honesty. I have no idea what's going on with my own privates, because of this. I'm not too open with anyone too ask someone face to face. But I'm thinking of discussing this with a doctor if it actually becomes a problem for me. Thank you so much for anyone who can help me understand a little bit more. :)