If you respect her, show it to her by waiting. Like has been mentioned, a very possible side effect of losing that are kids. THat woudl ruin you are life real quick at this stage wouldn't it.
As Synnen mentioned....work on the relationship first. At your age sex distracts your attention from all the important stuff. The stuff you need to be happy with when the appeal of new girl sex wears off, and trust me..IT DOES wear off. If there is nothing there and a kid happens. Well consider your days of having fun ended as YOU will be working to support the kid you created.
If its really love and not lust....you can have a nice family. But more times than not when you aren't already married...its going to be anything BUT fun and good times.