That really the only way she can win, she drops off and loses a lot of that power in the end game when people build up more. If your team fed, it happens sometimes teammate just are idiots. Also get early Banishes veil on here, makes fighting her a lot easier when you stop her kit combo from working as effectively. It's similar to Shaco from earlier, he needs to be fed to get off and get going, same for Leblanc, don't feed her and she loses a lot of that power that in the early game she had.
Also give me your name on League, wanna add ya.