Above all, do not disrespect your parents. Disagreeing with them is not disrespect. How you voice that disagreement CAN be. If you are (or she is) under 18, wait until you both are over 18 to do anything. When you both hit 18 or older, respectfully tell your parents how you feel and what YOU have decided, as an adult, to do.
f**k ur parents dude. who cares, life is short. forgive quickly, kiss slowly, love truly. just date her, in secret.(i wont tell:-)...promise. if you dont date her you'll never know. take risks. and have fun.