hi there, and welcome!
the perfect grammar in one so little is freaky, isn't it? my DD is now 8, but that was one of her things, too.
you'll get a ton of great advice on how advanced is gifted (not my area!) but what stood out for me was the testing/homeschooling.
we decided we'd only test when DD needed it for a particular reason - like a school program or access to services. she did one (horrible) year of traditional school for Pre-K, and then we had to pull her out in favour of homeschooling - the school environment was so toxic for her.
at that point we did informal placement testing just to see where to start, and (like you!) were amazed at how far up we'd have to go. that approach - just going where she needs to be - has been working extremely well. it's a challenge to keep up with her, and i'm constantly on the lookout for ways to deepen her understanding vs. accelerate more, so aside from Math, we're taking all sorts of interesting detours rather than following a set curriculum (though i do, as her teacher, have an eye on that as well so i know where she's sitting.)
... all that to say that to test or not test totally depends on what your goals are, i think!
DG
