I see there are already a lot here, but I'm just going to go ahead and post my own, then maybe I can get some advice from others that have already posted...?

it just seems as if my mother knows about me.  she's been really quiet lately.  either she's mad at me for not really helping out around the house much or... i really do think she knows.  so i'm planning on talking to her soon, before i move out.  80% of me is sure she won't kick me out.  i'm just wondering how to word things, how to tell her.

would it be better as...

i've been thinking and exploring for a while and i THINK i'm transgendered

i've been thinking and exploring for a while and have found that i AM transgendered

or

remember how you were hoping that i would be a boy?

i just really don't want to have to tip-toe around her so freaking much, i'm scared of getting caught - it'd be better to tell her rather than get caught, and chances are that i'll be under her roof for a while.  the chances of my fiance and i getting a place of our own, even with her mom trying to help out is slim to none (no credit, no rental history)... so we'll most likely be renting my mom's spare room when my sister moves out in january.  so what's the best way for me to go about clearing the air?  or would you recommend that i not really tell her?  should i hint / leave some suggestive things around?

Well I like the third one.  When I came out to my girlfriend, I started out by telling her "I thing I might be a girl inside".  That lead to a rather interesting discussion.  It was a spur of the moment think, I had not really planed on coming out,  But did anyway. 

Be brave and just talk with your mom. 

Best of luck to you

Beni

I told my mom (while she was alive....) in the privacy of her bedroom while Dad was at work...
"I think we should talk...I have been kinda unhappy all my life, and I think I know why now, I have done some research and I am pretty sure that I KNOW, that I am a Girl."
And that lead the conversation onword...

Thats what I think I said anyway....I really don't remember what I said exactly, but I am kinda in the same situation you are with your Mom as I am with my Dad...I think...

so I advise just telling her by the third option......but I wouldn't leave things around....