There are generally two ways to cure premature ejaculation - ie. coming before you want to. Both involve YOU developing a sense of where you are in the cycle and a willing/actively-participating partner. (1) There is the "pull out and squeeze the head of your dick semi-firmly between your forefinger and your thumb until the pre-orgasm anticipation feeling fades, then go back to fucking, repeat as necessary until you can sense where you are in the cycle and control it by slowing you rmovement, and your partner must leave you alone and not disturb you and must just wait until you're ready, or (2) "Stop/start" - when you feel the pre-orgasm anticipation feeling coming on, you and your partner come to a dead stop and lay completely still until the feeling fades, then go back to fucking and repeat as necessary until you can sense where you are in the cycle better and control things, mainly by your movements. Both methods work, I suggest you start with (1) and work your way into (2).
I can't stress enough that you must have a willing partner who actively participates by being still and quiet while you are performing these methods. If your partner is not mature and caring enough to lay there still and silent, and encourage you to learn, then kick her to the curb and find a more caring partner.
Fortunately you are young and can afford lots of experimentation and mistakes while working on this. Just be patient and have enough backbone to deny yourself the instant gratification. You will be rewarded if you work on this, and so will your partner.
Later in life you may have the oppoosite problem, difficulty coming, and again you must be able to develop a sense of where you are in the cycle.
Buy a copy of Dr. Bernie Zilbergeld's "The New Male Sexuality" and READ it. Bernie knew his stuff, and his methods work. You will find his detailed coverage of this subject in there.
http://www.nytimes.com/2002/06/21/us...sexuality.html