You better wait another year before trying to perform in any porn film.
Child pornography is defined by law as the visual depiction of a person under the age of 18 engaged in sexually explicit conduct.
Even if you lie about your age you shouldn't risk the long arm of the law.
As for making this an inevitable career? If I were you, I'd break off all ties with my parents and save them the pain and humiliation of the bad news. You maybe romantic minded punk-idealists but don't be so naive and think you're going to make a fortune with your found idea of celebrity.
If you and your girlfriend are fully prepared to live a very sordid and destitute way of life and take your chances with the Russian roulette game that is the infinite amount of STD's that engulf and flood the porn world then good luck to you on your endeavors.