I'm ftm transgender and I really like this girl and I want to ask her to the dance, She's really sweet and understanding of my situation, But I'm really shy I also have her number
Keep calm, be relaxed, take a few deep breaths and jump in. Try to start a conversation first. Be casual and when you feel like you've warmed up, pop the question. If you're too shy, ask a friend to pop the question for you or text her if possible. Texting might make things easier (idk).
This might be a HORRIBLY offensive answer, but girls love spontaneity. Ask the question, but don't be an idiot about it. Get creative.
You could say something like "Hey ______ I was wondering if you wanted to go homecoming with me?" or "Do you want to go to homecoming as my date?"