Technically by the United Nations standards you are both considered youths. As long as your age difference is not beyond each other like lets say 10 years then your fine no one will look down on you. Remember if you really like this girl then you should not be afraid about the opinions of other people. If you consider your feelings for her based on what other people think rather than how you both feel about each other then it cannot be considered love in a sense.

I do not see any reason why you should not go out with this girl. If you really like her you should not need other people to tell you whether or not to date her. Just follow your feelings and don't let other people's judgments decide your feelings.