How to bring up going on T with my parents?

I'm bigender (male and neutral) and I really think it's a good idea to start hormone therapy and start taking Testosterone. I really really want to, but I've been having confusion with my gender for the past year, but in the last couple of months I've settled on bigender and I really feel like this is right for me. But I feel like my parents are going to say no because 'I'm still figuring stuff out'. Any advice would be extremely helpful!