One point that some LGB people make that I think needs to be deconstructed is this. Some argue from an anti-trans point of view that a child or teen who is LGB, thinks that if they gender-transition, they will be heterosexual. Wrong for obvious reasons. You can be LGB and cisgender because gender identity and sexual orientation are NOT the same thing. Let us not forget that Alan Turing died by his own hand because he was gay and doctors tried to give him feminizing hormones and that wasn't who he was.
One thing that people need to remember, both cis and trans, is this. I reject the term "normal people" because I say people are not made with cookie cutters. There are gay men who are very feminine, and there are men who might work for an auto servicing chain who spend all day in cotton drill overalls and have grease up to their elbows by the end of the day, whose colleagues don't find out, until they have a social club do or a work Christmas Party that they're gay until they walk in with another man and say, "This is my partner." And neither of them are wrong.
To say that you reject the notion that "Homosexuality is not a choice," I can understand, BUT, as you say, you don't get to choose who you are, but you do get to choose who you want to be.
I also say to people that just like it is for people who came out as LGB later in life, just because a person who is trans comes out later in life, doesn't mean to say that they have to erase all of whom they were. For an example of the first, Fred Smith was born in 1946 into a conservative family. He finishes school and he does a year of an Arts Degree and a year at teachers' college and becomes a high school English and History Teacher. While at Teachers' College, he met a young woman, and they married after finishing. Perhaps, in Fred's mind was the idea that if he got married, he could avoid the draft. Two years later, Fred's first child is born. By the time Fred is in his 40s, he is a conservative looking man with a bald patch at his crown and hair that is turning a steely grey and he has a clipped and neat greying beard. Fred grows distant from his family, and his wife cannot understand why. When he turns 53, his wife becomes broody when it is announced that she will become a grandmother. Fred confesses to his wife that he no longer loves her and is leaving and she is shocked to discover that he has left her for a man. Fred shaves off his beard, and dyes his hair blonde. That's one example. On the other side, another Fred Smith, 20 years younger, got married and had two kids. Fred had bought his first Falcon, in 1986, and he owned a few others, over the years. In 2006, he can hide it no longer, and tells his wife that he is trans. Fred becomes Freda. But Freda doesn't have to take her Falcon to the Nissan dealer and say that she wants to trade it in on a Nissan Micra and have the tray under the passenger's seat so that she can have two pairs of high heels and other shoes in it. She might wear a little bit of lipstick, when she's going out and keep her Falcon. She might even opt to wear jeans and t-shirts instead of dresses, but she's still a transwoman.