I'd say that once she split with Hank, she came into her own as a character. She realised she wasn't a flighty teenager any more, didn't need to be part of a couple to be a successful superhero, and had the potential to be a leader.
No she didn't. We got no scene with her coming to those realizations, and very often she continued to do "ditzy teenager" things. She just spontaneously went from point A to point Z, skipping any kind of actual progression/growth.