DS flew through quite a few years of math also. We were using EPGY but after having some issues with their Geometry course we began using AoPS and it has been great. For most of their courses we buy the book and have him independently go through the book and work the problems and then he does the online course. It is better to be present during the online course but you still have access to the transcript if you cannot make it. This has also helped ensure he has a solid mastery of the material and served to slow him down a little.
You might also want to have your DD try to work some of the AMC 8 and AMC 10 contest problems and try to enter some math contests. DS has done pretty well overall but it can be eye opening to see how far ahead and how quickly some kids can solve difficult problems.
