Hi Vinboy:
The foreskin is not attached to the underlying shaft so it can glide back and forth. When you foreskin is behind the head, then you will have a lot of loose skin making folds. This is normal. The loose foreskin is free to glide back and forth, which many guys think is very pleasant and enjoyable.
It sounds like you have a full-length foreskin.
Many guys would envy your foreskin even though it does not automatically retract. You display great wisdom in wanting to avoid circumcision.
The foreskin is an asset and highly beneficial. A full-length foreskin is more of an asset and more beneficial than a short foreskin. Moreover, the ancient Greeks considered a long, tapering foreskin to be a sign of male beauty. The long tip is called the akroposthion.
The extent to which the head of the erect penis is visible depends on the length of the foreskin.
Long full-length foreskins will not auto-retract on erection. Only inadequate short foreskins will auto-retract. For your skin to go back, the foreskin has to be wide enough to retract over the head.
If your foreskin is wide enough, it will retract if it is shorter than the erect penis. If it is longer, then it will never retract by itself but may be pushed back, however, it may not stay back. Some full-length foreskins spring forward again when released.
When a full-length foreskin is manually retracted, it gathers in folds at the base of the penis. The folds want to unfold and push the foreskin forward back to its normal position. A full-length foreskin is likely to slide/roll forward to recover and protect the glans penis when it is released. Some men simply cannot keep the foreskin retracted. This is not considered to be a problem.
The full-length foreskin provides superior protection to the head of the penis and keeps it soft, smooth, and sensitive.
The full-length foreskin may improve the sexual experience because of its superior gliding action. The full-length foreskin also may have more pleasure nerves.