While Jespah gave you a very good answer while avoiding issues of faith, I will add the faith component just in case you asked the question from concerns relating to faith.
Full disclosure - I am a christian and believe pretty strongly in my faith.
So, from my perspective, any sexual intimacy outside of marriage is not okay. If you want to be accurate, I believe it is sin. It is outside God's plan for His creation. I don't intend to go into why I believe God intended sex to be only between a married man and woman, at least not in this thread right now, since that is not needed to answer your question in the simplest manner. But I believe relationships are healthier and stronger (for the most part) when a couple waits to have sex until they are married.
But, it is a decision each person must make for themselves. If you do not consider faith in God to be a big deal and you have considered Jespah's points, then it is okay if you decide it is okay.
One other point would concern your age. I really do not believe most teenagers are capable of making the informed decision of when to begin having sex. I believe that unless a teenager is old enough to sit down with his/her parents and discuss it, then that teen is not old enough to have sex. Just my personal belief.
Hope you make the smart choice and correct choice for you. (If this question was asked from the perspective of you contemplating sex for the first time.)