Until she gets to college it's gonna be real rough, like there's days I wonder if it would be better to advise you to go get a few dozen ofthese
before a new lens.
If you want good shots of her, I'd say find a way to get into the gym with nobody else around and pull out the flash. Or wait for meets at bigger event spaces with better lighting, or a gym with some windows that aren't sealed off (last meet I went to in the spring last year had ice big windows all sealed off with brown paper block all the light I was so excited driving up and so annoyed when I got in). Last winter I shot some college gymnastics that are at a similar skill set to level 9, when I got up to 1/450th it was manageable, but still rough, and everything ended up with way too much noise; I've since upgraded camera, some lenses (will likely be adding another fast lens before things get underway) and memory cards. My suggestion for approach would be set your lens wide open, and keep a shutter speed of 1/500 to 1/1000 shoot RAW, try and get the ISO to being one stop over exposed, then pull it back and not be noise blasted, but for the amount of light at those shutter speeds you're more likely looking at RAW, 1/1000 wide open (1250th is ideal as a minimum), max out the ISO and then boosting a stop or two to get a bright enough exposure, then going through some of the more elaborate noise reduction methods to keep that under control.
Other things that helped me were a monopod to keep my arms from getting tired and getting really close to apparatus so that I could go wider focal lengths, depending upon the gym layout this may or may not be an option, but I've found I can get a little more light, a little faster shutter, larger DOF and a little different look.