I remember when I was at the point in coming out where you are now. I had a lot of the same thoughts, including that feeling of deceiving people - not being able to be the girl they expected me to be. It made me shy and reluctant to open up to anyone. So people thought I was boring.
When I did start opening up to people, everything started to get better. When you're open about things that are hard to talk about, people tend to respect your courage. You also become a more interesting person in the eyes of other people. And of course it's a great relief to be seen for who you really are. Personally, I'd rather be rejected for who I really am than accepted for seeming like something I'm not. But, realistically, being confident enough to open up to people makes you a more likable person. There will always be people who choose to reject you for their own random reasons, but I think you'll see that after you come out, it'll be easier to form friendships that are genuine and lasting.
It does get less scary. I have a lot of respect for the way you're coming out to people. I took a much slower, easier route. I started with close friends and waited until it came up naturally in conversation (like: them - "Well, you know you're not like most other girls." me - "Yeah, I don't even see myself as a girl. In fact, I might transition."). Once I had support from a core group of people, it was easy to come out to people I didn't know as well. I would have found it challenging to begin the coming out process by talking to teachers and classmates about it. If it got easier for me, it'll definitely get easier for you!
Good luck with everything! And if your TA takes a while to write back, don't get too scared. It's likely she's never had to respond to an email like that before, so she might need some time to find the right words. It sounds like you're off to a good start.