In the end - it's ultimately your choice. Hair grows back. Clothes can be changed. You can ditch binders and go back to regular bras. None of it is permanent. Sit your mom down and tell her you just want to explore yourself. If she doesn't want to hear anything about transitioning, humor her and let her think it's a phase for now.
It isn't like you're going to run out of time and it isn't a rush to fully transition.
If, once you start trying to pass as male, you decide you want to go further OR that you think you'll continue transitioning and want to be male full time TELL mom that you want to see a professional to help get your thoughts in order. A psychiatrist or psychologist will be able to help you with the change and will be able to help you handle your mother.
Bottom line is it will be your life. But you do have to live with mom in the mean time. If now isn't the right time to push it, then consider waiting until you're independent and well on your way to moving out.
I've been actively transitioning since late 2009 though i gave up feminine stuff long before that - it was never my thing and i did it for my dad. It isn't a fast process, at least not medically, and shouldn't be.
Do some research. Look for support groups. Look for other people in your area that are also TG/TS (but be safe about it.) Talk to your doctor and look into counseling of some sort. If you want to change your appearance, then as i said before - do it, it can always be changed again.
