I'm interested to hear other peoples input on how to bring up the topic. I do think my mother would be supportive of me, it's just we're close, but we weren't raised in a way where emotions and feelings were really talked about. The only time I can remember my mother out right hugging me or saying I love you aside from when she found out about my self-harm, but still she didn't really press me on it.
I'm really bad at expressing thoughts about myself or any emotions really, but it doesn't feel like a letter would be appropriate as we live in the same house (I'm 18 and kind of extremely socially awkward), but i just don't know how to bring up the topic, "Hey ma, what are you cooking, and btw I'm transgender." As a side note my mother has stated before that she wanted a son and two daughter but got two sons and one daughter, when I heard that the first time I kind of smiled a little.
Oh, the last thing, I think she might have a vague idea because I wear nail polish/mascara, and am a little effeminate, but she may just think I'm gay. Sorry for the slightly rambly post, I didn't have as clear of what i wanted to say, but i needed to say something.