The only thing you leave behind when you die is what people think of you. You can do your best to be the master of that in life; if you're good you hope that people will remember that you are good. But it's never entirely in your control. In this instance it is likely that she will be buried as a he, in clothing that she would not have liked and in a manner that is disrespectful to her life and to who she was as a person. That is the ultimate tragedy and it befalls many people; if you are eulogised as a person that you were not, then it's almost as if you were never 'you' at all.
The other issue related to this, is the general disregard for the rights of children in society. Children have rights as people independent of and contrary to the rights or wishes of their parents. This is a normal part of human development. It is unfortunate that their wishes, even when expressed, can often be disregarded particularly on the cusp of adulthood.
Ugh. I forgot about this. She was 17 so her POS parents will put her in a tux and send her off to Jesus... Absolutely horrifying.
