I'm just a year older than you, and I know what it's like to be in love, and feel like this is the only person you want to be with forever. Once you've introduced yourself to things that are sexual, there's no going back. Even worse, I know some girls that because they've had sex with their boyfriends, can't go back. Once you've given them that that will be all they want.
Believe me, I really thought I could be with this person forever. But the things we did, weren't of God. And if it's not of God, if you don't let GOD be in charge of the relationship, then it will end. Your relationship is only as strong as you let God let it be. Only His strength will keep you together forever.
I'm still a virgin, but I have done a few things that I won't be able to give to my husband as my first. One of the biggest things I regret is that God and I are no longer the only people who have seen my maturity. And I kick myself everyday for it.
At least when your married, you won't have anything to be ashamed of, or regret. Because once the union is under God, things are magical
Listen to the older guys here (newseed, etc), they know their Scripture and have been there before in a sense (that age i suppose).
If your boyfriend doesnt understand your decision to not engage in sexual acts, then he doesnt love you as much as you think he does. True love comes from God. Everything else is human love and falls waaaay short.