Does she sound like she is full of herself or what, y coworker?

Wow, lol, you know what, just keep letting her make a fool of herself, you're trying to give her advice, and she is not listening anyways! By what you said, I'm surprised she got that job in the first place. She IS very y, and sounds like she is just trying to advance in the workplace, maybe her y-ness will pay off, who knows?!