Is Inability To See The Head Of Uncircumcised Penis During Erection Normal?

Hi, I am 24 years old, I have an uncircumcised penis, for some reason, I never knew male are meant to roll the head foreskin back during their teenager period. After talking to a few friends, I only realise I should able to see the head of my penis whenever I have an erection, but all I see is my skin....and I am not able to have sexual relation with my girlfriend, and of course I am still a virgin, just wondering what should I do. thank you very much