Relax. ust relax.
I was.. let me think... 23 or 24 when I started my first relationship (with kissing and such *g*). My partner was two years older than me and had never dated before, too, and I didn't think "Uh, what a jerk he musst be if he never dated etc.!"
I believe that your feelings about this girl are just normal for this time... you're attracted, have perhaps some butterflies in your stomach etc. Many, many people feel like that! Even if they've dated before.
Continue to see her, don't get your hopes to high - not every nice girl turns out to be THAT girl, but can be a good friend, too! Have fun together, and you'll be able to sort your (and her) feelings out in time.