@jayjay00,
Don't do anything behind the back of her or your parents - they'll find out, trust me and then it will backfire on you.
Involve your parents and ask if they can drive you to the movie theater and pick you up later on. So at least you will be "alone" in the movie theater.
By the way, I am a very open mom, but I would have never allowed my daughter to date at 12, let alone to a boy who is 2 years older.