she's clearly gifted. so, now what do you do.....
I'd start by scheduling a meeting with the principal and asking for her help on keeping your daughter challenged - don't even mention the gifted program. rather, go in with examples of what your daughter can do and where your daughter needs help (i.e., she's bored out of her mind in class, you need suggestions on reading material, etc.). if you have a good relationship with her current teacher, see if she can join the meeting. the point being, you're not trying to undercut the GT teacher, rather you're asking for solutions to an identified problem.
And, you should get a good response. Under No Child Left Behind (which I prefer to call Every child left behind), every school that takes federal money as to provide an appropriate education for every student - not just the lower end....At a minimum, you should formally request an ALP (advanced learning plan). Actually, the prinicpal should offer this at your meeting.
If that doesn't get you anywhere, you might consider doing private GT testing. In the Denver area that runs from $500 to $1500 depending on who does it and how in depth the testing is. In Colorado, a parent can also request, at any time, that the school district administer a GT test. If it is not part of the "normal" testing protocol, then the parent is asked to pay for it, but it's less than private testing (about $150 in our school district). So, something else to investigate.
FYI - most GT tests have false negatives but not false positives. So, it is likely that she tested lower than she is. Your GT coordinator should know this. If you ever get to where you're pressing it, I'd ask why the GT coordinator relies so heavily on a standardized test. Our district uses three pieces of information (test, parent impression, teacher recommendation) and I've known kids that did not have good scores get in due to parent and teacher observations. Our district feels parent and teacher impressions are more important than the test scores in identifying GT kids.
Even when in a GT program, you'll have to supplement a ton at home (as you probably already know with your older ones...). It just takes a lot to keep these kids engaged - musuems, after school programs, etc.
GT kids are a blast and a hoot but they are definitely not easy to raise. Good luck!