I'd say that whether it's worth the trouble to do a screening depends on what you're hoping to accomplish with it. Typically we're talking about testing, DYS, and the like in order to find the right educational environment for our kids, because we've decided to send them to school for a variety of reasons, and we're trying to prove to them what we already know about our kids.
Since you've already decided to homeschool, she gets to move at her own pace, and it appears to be an appropriate environment... where's the problem?
To answer your original question: In my unprofessional opinion, that does not sound like, "just 'bright.'" There are some things you've posted here that sound very similar to my own gifted "first-grader."
