Be self-deprecating about your high school self.
We were all lame in high school. Everyone's hair sucked. Few had game. All the clothes came from Structure.
The best way to capitalize on how uncool you were? Laugh about it. Adolescence is ripe for jokes. If you get too glory days on her, she won't listen to you—because you don't look or sound like Bruce Springsteen.
Add a little levity to the most awkward years of your lives, and you'll have an entertained woman on your hands. The road to hot sex is paved with belly laughs.