16 years old and foreskin does not go back over the glands or head of my penis. should i be concerned or let nature pull it's course?

Phimosis at 16 years: By 16 years the foreskin should have retracted to expose the glans penis .Please consult your pediatrician and ask him or her about using betamethasone cream to soften the prepuce

Here are some ...: If long foreskin hasn't bother you and you're able to pull back for regular hygiene, do nothing with it; if bothering in whatever may be, skillful circumcision is needed. Usually, I only excise the redundant foreskin and leave the subcutaneous tissue as much as I could so not to disturb local nerve fibers leading to impair the sensation of glans penis - though rare but happened. So, see Doc timely