Do you doubt me? Let's examine the evidence.
1. Anne spends a huge portion of her books quoting from other books. You cannot tell me that fangirls don't just walk around making references to things CONSTANTLY.
"My life is a perfect graveyard of buried hopes. That's a sentence I read in a book once, and Isay it over to comfort myself whenever I'm disappointed in anything." - Anne of Green Gables, Chapter 5
2. Anne starts a "story club" (read: olde-fashioned fanfiction) with her friends, and then supplies most of the plots and characters.
If there is a group of fangirls who all belong in the same fandom, one comes up with the fanfiction/headcanons, and the rest approve or disapprove. Also, in the book, Anne cries not only when they read the stories in the Story Club, but Anne actually cries when she writes. She's got fandom feels if anyone does.