Dear Jilian,
Hi welcome to Susan's Place. It sounds like you are doing a lot of things correctly. Thank you for your accepting attitude and the love you are showing. I look back at my own desperation and think of what was important to me to know. I really needed to know that a good outcome was possible. Being trans and not being yourself is like carrying a ten thousand pound weight around with you. With your daughter being so young, I would say present her a glimpse of a future where she can see her being herself, being happy and surrounded by supportive people. It is so important that she has hope to achieve a happy future. Yes, she will go through some things, but they are doable. I know you have your fears as a parent. I am a parent as well. Show her you believe in her and her future. Don't have your face be one of all your fears. I think it is incredibly unlikely that she will do a right turn from what she is telling you now. (I'm no doctor.)
I would urge you to keep talking to us here. It is a safe place and there is a collective wisdom that comes from experience. Speaking as someone who doubted it was possible for me to face this, I have transitioned and am incredibly happy because of it. Oh, my name is Moni, short for Monica. If I can ever do anything to help, I would be happy to do so. Hugs to you, Mom. Hi to your daughter.
I think the Girl movie shows how powerful the drive to be yourself is, but the ending is disturbing in my opinion. It might do more to heighten anxiety than help, when first starting to understand this. My thought.