I don't know if I can help, but I sympathize. My daughter is also 3 and we've struggled to find materials that are appropriate for her. It's hard to find things that are complex enough for her brain but simple enough for her fine motor skills -- for example, she can't write very well. She's already doing kindergarten-level material at home and sometimes elementary school material. I work with her part of the time and we have a nanny who used to be a preschool teacher who is with her when I'm working.
I am a curriculum designer professionally, working with museums, textbook publishers, and nonprofit organizations, so I put together my own materials for my daughter, using various sources. I might be able to help you find some materials for your son. Can you tell me more about his interests, learning style, etc? You can send a private message if you'd prefer not to share too much publicly.
