Reddit mentions of Annie on My Mind

If you don't mind reading adolescent/young-adult books, there are a few that really stand out:

Swimming in the Monsoon Sea is an interesting look at Sri Lanka's view of homosexuality in the 80s, and how a teenage boy comes to terms with his sexuality in that culture.

Luna deals with a transgender teenager, from the perspective of his (her) sister. Peters' other books are good, too, and often deal with LGBT issues.

Annie on my Mind is an important novel in the history of LGBT adolescent literature. It was published in the early 80s, and has been banned and censored over the years. Definitely a must read.

Boy Meets Boy is utterly fantastic. It's a very happy little novel that follows a teenage boy as he falls in love with another boy at his school. What makes it unique, though, is that the "queer" aspects are treated as normal in the town. It's an improbable novel, but oh so sweet and cheery. Definitely pick this up if you haven't read it yet.

And of course there are more, such as The Misfits, Letters in the Attic, and The God Box, that deal with LGBT issues to varying degrees of success.

What helped me a lot was actually queer YA lit, and having a gay/straight alliance at my high school. It's really great that you support her! You could throw a couple books her way... this is my list, I'm sorry I don't know any books in other languages!

• Annie On My Mind
  
  
• Keeping You a Secret
  
  
• Love and Lies: Marisol's Story
  
  
• Oranges are Not the Only Fruit (this one might be harder for her, especially if she struggles with English!)
  
  
• Rubyfruit Jungle
  
  The last two definitely cross over into adult lit territory. I've read all of these books as an adult and most of them as a teenager - I found them very sweet and relatable. They made me feel that falling in love was really possible, despite the limited number of gay women I've been surrounded by :)
  
  You could also, when she is of age, go to gay bars with her and play wingwoman.