Re: long and sorta tight foreskin
Some guys have short foreskin while others have very long foreskin. In either case, they should all be able to pull it all the way back. The length of the foreskin does not matter in this case. The reason your skin is not coming back is probably from a condition called phimosis. All that means is that there is a tightness around the opening. If you look up the term on this site, there is a sticky in another section that teaches you stretching techniques to help widen the opening.
If you have an open relationship with your parents and / or your doctor, you can talk to them about this. Doctors sometimes prescribe creams that help soften the skin which helps it stretch better. In most cases, this can be fixed without circumcision. If you have a doctor that wants to circumcise, you can always talk to another one. I know you probably have some limits with that at age 16 but as long as this is not causing you any problems, you can wait until you are 18 to treat it.
One final detail, you somewhat implied that this problem is only when you are erect. Can you pull your skin back when you are not erect? If so, try to make sure you keep everything clean underneath the foreskin. Proper hygiene is important to prevent infection and odor. Most people suggest using water or a really mild soap. Stronger soaps sometimes cause irritation.
Good luck to you.