Welcome slhogan! Glad you've found the right thing to engage your mathematical DS. I wonder whether you'd expand on your questions a bit - e.g. when you say "what next?" is it that you have concrete concerns about the order in which to do different kinds of maths with him, or is it that you have plenty of maths background yourself and can happily decide that kind of thing, once you've got over your shock at just how far ahead he is? One thing you might like to look at is lots of problem-solving stuff, e.g. an appropriate choice of problems from
http://nrich.maths.org The other thing I wondered is what you were hoping to get out of testing for DYS and DYS itself. If that whole process is going to be very expensive, and given that you're homeschooling anyway, i.e., don't (right now at least) need DYS help in advocating at school, is it going to give you value enough to be worth what it costs?
