I sing too deep?How to make myself a soprano?!?

So i guess I'm an alto but my old voice teacher said I'm a soprano.But I was singing "I go to sleep" by Sia and My friend said I sing it really low, and deep. >_> Damn it! First I wanted to sing deep but now I want to be a soprano( but still have the ability to go really low which I can and my neighbor can't >_<) What can i do to sing higher!?And develope a cool kind of singing style!?!? :D