When I was in your shoes, I googled "math placement test" and "reading placement test" for help piecing together where we needed to start. There are loads of free things on the Internet--some more useful, some less--that can at least give you a sense of what's too easy or too hard.

Curricula like Singapore Math offer their own free placement tests which might be worth a look, though they tend to present things their own way, and this might not translate very easily to other curricula.

Kriston