Hi Paige,
I received a birthday card from my mother yesterday, addressed to "My darling daughter". She has been totally accepting from the beginning fortunately. But I think that when writing everything is just that bit more considered than when we speak. When we talk she still occasionally gets pronouns wrong, despite me coming out to her over two years ago. It used to get me angry at first because I thought she was either resisting or simply didn't care enough to get it right. But in reality it's just a very difficult habit to break.
I hope in time your parents come around but in the meantime it might actually make your life a little less stressful for you if you cut them a little slack. Over time you will probably find, as I did, that it is hardest for those that have known you the longest. Children and new friends and colleagues almost never get it wrong, in my experience. That doesn't mean they are trying harder, it just means they don't have much previous interaction to overcome.
Obviously I don't know the detail of your family life, and I am aware that I have been luckier than many other girls, so I apologise if I may seem to be trivialising your experience. That is not my intention. But my advice to you would be to try and stay calm, take comfort where you can from the small signs of support from those around you, and try not to take umbrage over some minor things that you may even find yourselves laughing about in years to come.
Best wishes to you. xxx