Dude,
I have been with other people besides my wife. Do you plan on getting married? If you do, my advise is wait. You are not too young for sex, but sex is something very very special between two people. If you have sex it WILL affect your relationships in the future. Now you may be saying I am going to marry this woman, but truth is you can't be sure of that till you do. My advice is don't have sex just to have sex. Have sex with the woman you love and marry. Just my advise, take it or leave it, but I can tell you from experience the problems it will cause for the person you finally marry are not worth the experience now. Trust me. I have been where you are.
Also, I have two friends who had sex at a young age. They both got there gf pregnant and the used protection, condoms. The both work minimum wage jobs, one is married, one is not. One pays child support and will for 16 more years. The other is very unhappy with his life becasue his child has taken his youth away from him. When all his buddies are going out having a good time, he is working to put food on the table. He loved fast cars, but he drives a Tercel because he can't afford anything else. I also have another friend. He was smart, he waited till he was much older and has had sex with only the woman he is married too. He has a good job, makes good money and drives a really nice car. He has a great wife who respects him in this area because he felt that sex was special enough that he kept it for just her. He has a great life. He deserves it, he did it the right way.
Best of luck man.