I finally told her...
My mother and I were talking about god knows what, I let her shoot the Nerf gun I just got (Recon CS-6 with the Massacre Mod for those who are interested haha, I am such a dork!) and I just felt so comfortable that I told my mother. I first told her that she can't tell my dad. I love my dad, but he'd be so heartbroken

Then I told her that I'm not gay. And then I asked her if she knew anything about people who get sex changes. And then she looked at me weird... I told her that I'm one of them... She said no, I can't get a sex change. But she said she knows why I'm transgender.
When she was pregnant with me, everyone thought I was going to be a girl. Everyone addressed me (when I was not yet born) as "your daughter" or "the girl". Perhaps it tricked her body into thinking that it was raising a girl and it treated me as such. That must have caused some hormonal imbalance or something.
I asked her if she's going to have trouble sleeping that night. And she said no because it's not a big deal that I'm transgendered. And that I'm still her kid

But it's bittersweet I guess. I wont be able to be who I am. And I can't wear her clothes in secret anymore, since she'll be extra vigilant. (But I have girl friends to do that with lols. It's more fun because you get to dress up together lols)
But strangely enough, after I told her, I don't really feel like a girl as much anymore. Of course, I'm still not happy with my body, but I feel it's more or less resolved? But then, if I could wake up as an attractive girl the next morning, I'd be more than happy