This is a delima. We all go through these times of thoughts, I think.
I've talked about my Gender Identity with my dad when I was about 23, and while he was suprised, he seemed ok. We never talked about it again, though.
My mom caught me wearing her make up when I was 14 and I was so scared and thought I was a freak, I suppressed everything until I moved out and lived on my own. I think if I have the conversation with her, she'll be upset, but will learn to accept it.
My Brother, on the other hand, I think would be a problem. I care a lot about him and my niece, but he's always been a very macho sort. He is even in a bike "club". I'm afraid of what he'd think and do if I were to tell him. In fact, he's the only reason I've not talked to my family about my gender.
It's very tough. I have no real advise for you, I'm afraid. But you have someone who loves you and says they care for you. Perhaps you should trust that they'll be there for you during the transition. Do what you you feel is best for you, not what others feel are best for you. *shrug* ... I feel like it's the blind leading the blind, here.