I don't understand why as a rule we're always trying to classify people and because of that it doesn't really matter if we think of her as straight or bi. And I really liked the heteroflexible category. I had never heard this one before. Now, having said that, I myself think of her as straight. There is nothing in canon (as far as I can see) to indicate otherwise. In fact, she doesn't seem to have many close relationships of any kind with women.