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I completely empathize with you. The problem of premature ejaculation is quite common and is distressing to a young man but is seldom discussed.
See most of the time the problem is secondary to the anxiety attached to your expectations in the bed. It has been wrongly projected by unscientific magazine articles and porn that a man can last for 30 minutes or more. Honestly, most of the male ejaculate before 5 minutes.
When you are anxious about not lasting long in bed, you actually do not enjoy the act of intercourse and keep on thinking about prolonging the act without enjoying it. The preoccupation and anxiety about not lasting enough, in fact, cause hyperarousal and lead to premature ejaculation.
Moreover, when the male start to thrust himself into the partner the moment he undresses leads to early termination of the coital act (the sexual union that takes place between male and female during insertion of the penis into the vagina).
There are also lots of young men who are suffering from premature ejaculation without any associated anxiety or apprehension. Such men as well as you may benefit by taking oral medication like tablet Dapoxetine or Paroxetine before the sexual act. But in your case, I would like to suggest relaxation techniques like breathing exercises and progressive muscular relaxation.
Regarding your problem pertaining to the non-retractable foreskin, my opinion is that you must consult a surgeon. It is always better to remove foreskin if it is causing inflammation or itchiness.
Non-retractable foreskin is often associated with problems of genital hygiene that may subsequently lead to chronic infections. So make an appointment with a general surgeon.