Need help with my mom?

I am 13 years old, and I have the Gothic style. My mom is totally against me being goth, she keeps denying it, and i keep telling her to accept me. I am not slutty, In fact I'm really shy. I like to wear my black tutu with black leggings, and it show no skin. But my mom says it is inappropriate for my age. I want to know what you think. I need help on how to make my mom accept me. and if i try to tell her my feelings i just get punished. I'm also a 4.0 student.