Well, for starters. I'm 21, I've been bisexual for years, but have begun to become almost completely sexually attracted only to men, everyone already knows about that except my parents. But only a few people know I'm transsexual and am working on starting HRT right now, seeing as how I still live with my parents right now and am still on their health insurance, its necessary to come out to them about my transsexuality.
I do plan on moving out soon, but I have tons of clothes, I go out as a girl as often as I can (i don't pass well right now because my wigs dont work well with my face shape, and complexion!)
I have no question about who I am, I have been this way since as long as I can remember, and I'm almost 100% positive that if I put it off any longer, that I will end up regretting it heavily.
My dad is more understanding, he used to be catholic but converted to christianity for my mother.
My mom on the other hand is very religious and is christian as well, she found my outfits sometimes and would be disgusted and such, but recently she asked me in the car if I was trying to be a girl or what not, she was questioning it herself, so I've begun to think that she's becoming more eh.. understanding of it I guess, and would be less shocked at this point..
I have plenty of support from all my friends who want me to be happy and are looking forward to me starting hrt!

And I go shopping for my clothes with a lot of them =]
I'm just very worried my mom will cry or freak out and such when she finds out and she's been upset a lot lately so it makes me more hesitant, I don't really want to be the cause of her being upset.
Advice???