Her 'threat' to the Hall quoted in your post, and similar threats to Tuon in the next book, really portray that Egwene genuinely believes that if things don't go exactly as she wants, the Last Battle will be lost and humanity doomed.... if that isn't symptomatic of a big head I'm not sure what is!
But at the same time, her words suggest that she would happily throw the Last Battle away if she didn't get her own way. It comes across as if anything would occur to dent her pride / power, then that price is just too high, regardless of whether it may mean the difference between winning and losing the Last Battle.