I think it interesting that Catherine is experiencing this "gray" now going to a new place with new people. I could imagine she might have run into this at home, if there had been sibling rivalry, other good but artful friends at home. But she was brought up, even though the eldest daughter, to be humble (almost pretty), to have hung out with brothers and not taught the refinements of society yet having the respect of being a clergyman's daughter. She was probably just considered "one of the brood" at home, since she didn't have any remarkable traits except for being a good kid. And being a good kid is a great way to launch, but all the anxieties come because she hasn't been shown the ropes outside of Fullerton where she grew up. Since she is artless, and we don't see that she has run into any artful people (artful versus artless has just come to me lately on this... maybe that's why she's can't draw!), she needs some time to figure out that just because someone puts on a front of self-confidence, that doesn't mean that they are confident, know what they are doing, and are good people. The Fullerton "rules" dictated that in the past, but Bath is different in that way, although she may not have figured that out yet.