You might want to check out a broader diagnosis of learning disabilities. The inability to process more than a one step direction, or copy or draw a shape may indicate a learning disability of some sort.- Children with a diagnosis of learning disabilities have brains which process information differently than "typically" developing children. We are learning more about the different kinds of learning disabilities that kids can have, and how to deal with them effectively as parents and in the educational setting. Did your neuro recommend any specific services/therapies for your son? Typically, an Apraxia diagnosis indicates a problem with coordinating our small, fine motor muscles, like those around our mouth that control our lip and tongue movement, impacting speech production/output. Perhaps your neuro is using it as a diagnosis with regard to the ability your son has to control the muscles needed when writing.
You might check out some of the sites dedicated to learning for children who are autistic. I am not in any way suggesting your so is autistic, it's just that these sites are full of good information about the various forms of learning disabilities and their therapies or treatment.
Become a passionate advocate for your son, and learn as much as you can to make sure he receives the specialized therapy or education that he needs. Locate and use every resource that you can to make sure he receives all of these services necessary to learn and thrive in his life.
Also, know that you are not alone- there are many children who learn differently. It won't be easy, but you can do it!