Is it better to date when you are older?? Long, but please read?

I've already been dating this guy for 10 months. He's my first boyfriend, but I'm his fourth girlfriend. He says I'm the only girlfriend he's had that he's ever loved though. He's a nerd, but not the kind that wears glasses, is unattractive, and sucks at relationships. He's actually really attractive, and is really good to me. I'm the kind of girl that's in the popular crowd, and lots of guys hit on me because supposedly I'm "gorgeous" (although I don't have high self-esteem so I don't agree with this.) This guy and I are basically total opposites. He told me he's always thought I was way out of his league. I know a lot of really attractive guys that every girl wants, but I don't want them, I want this guy. This guy I'm dating wants to marry me someday, and even though we're young I feel the same way. But he has confessed to me before that he is sure I'll find someone else. I was thinking yesterday that it might be better if we dated when we are older, and I kind of discussed this with him, and he said he'd wait for me. So if we dated older, would it be better? Thanks!