Well, I think back on the book (mistake, I suppose), and Lisbeth states in inner contemplation that she doesn't tell people about certain things at two different points in the story (I think this should be vague enough not to give away plot points for those who've not read the book) and gets her in trouble because, simply put, she didn't think anyone would believe her story due to the way she looks. She had no sexual confidence through most of the first book, stating pretty much that she gets a pity or drunk *. She doesn't really assume a sense of sexual being or empowerment until the first couple chapters of the second book, which will likely be cut from the movie as it did in the Swedish version, assuming the American sequel gets made.