Re: question about an uncircumsised penis
Yes, you should be able to retract the foreskin. I'm also uncut and have been able to retract the foreskin for as long as I can remember -- early childhood or maybe from birth. (I'm 59 now.)
When I was about your age I had a friend who had your problem. I think for him it was painful to have an erection. (Hard for me to believe he let it go that long, but I got the information 3rd hand -- from his girl friend to mine to me.)
I believe the fix was for him to be circumsized. I suggest you ask your doctor about it. It shouldn't be too difficult to correct, and your insurance, if you have any, should cover it. Don't be embarrassed to ask. I know at my age I didn't want to see a doctor about anything "down there", but there's really no reason to be shy with your doctor about it. Just do it.
And I wouldn't worry about the pain either. I've even considered having it done at middle age, when I remarried and my new wife wasn't sure what to think of the "extra" skin. She got used to it quickly so I kept it, but I'd not hesitate to have it removed if there was any problem with it.