If you made a soft way in the past.I think now you need a hard way, a very serious conversation.
I am 21 years old and i have no passion. So i think you re very lucky to have the love of dancing . It your life, your choices. I mean almost people have to do a job that they dont like it, for 40 years. When you re 18 and go to university, your dad cant forbid you any more. So anyway you can go to that dancing life with or without his permission. So why your dad not let you do it.
Show him your love, show him your passion, and if he dont accept, tell him you will do it with or without his support. That the only way you can live the life that you re happy.

Im just the guy 's learning English so sorry if my word is hard to understand, and thank for reading my thought.