I have a question for you to ask yourself.
What is actually stopping you from beginning your transition?
That was the very first question I was asked by my therapist after I told her that I am transgender and need help.
I can understand your family not believing it. That's called denial, my family suffers from it but that denial phase for my parents is in its final gasp for air as they are beginning to accept the new reality of seeing me actually happy and in a good mood when I am myself at their house. It takes time for that to happen and in most cases its how you present yourself to them. If you only dress, act ...ect male, then how can you expect others to believe you? That was the epithany I had not too long after I came out and wanted to show them the real person that I am.