I'm very proud of you and your beliefs, and I say that as a 28 yr old male, ma'am.
The important thing for you to remember is to stick to your belief system. This type of issue can be a very difficult one, especially at your age. However, if he truly loves you, trust me, he would gladly abide by your wishes in this type of situation.
You sound like a special girl, one that should be proud of what you believe in. Ten, fifteen years down the road when you are married and have your family, I would assume that you'll be very happy for waiting until marriage with this type of thing. It's who you're with when you'll be 30 that counts, you know. We tend to have so many different definitions of what love is when we're younger, but it still remains that the most beautiful example of it that I've ever seen is when you happen to come across an 80 year old couple that's still in love and holding hands after 55 years of marriage.
The day will come when you too will be that old, and sitting with you will be an old geezer that you've been in love with for decades~. But you'll still love that same old geezer (~) just as much as you ever did, and more, you know. That's what life's about in this area, and you sound smart enough to know the truth about all of it, and I'm proud of you for that because that's a rare thing today.
That said, you have to have enough faith in your own heart to know what's right or wrong here. If you truly believe in what you do, than the relationship should be on your terms, you know? You deserve that, I think. And if it doesn't work for him that way, you know, that might say something about the situation for you, too, even though he sounds like a great guy.
But the bottomline, I guess, is that you should always try to stay loyal to the message coming from within your own heart, at whatever cost that might be. That's just the way I'd look at things if I were you, I guess. Good luck, God Bless.