DD9 has very similar characteristics, with diagnoses of SPD (definitely) and dysgraphia (I'm somewhat dubious). She does better with math when she is allowed to write on graph paper - that's definitely something you could ask the school for. Does he also show executive function deficits (planning a project, estimating how long things will take, organizing his papers, etc.)? DD9 has those, too, although she has made great strides this year with a supportive teacher.

I would start by looking for an OT nearer to your home who specializes in SPD. It sounds like the one you saw probably wasn't a good fit. I wouldn't travel for a treatment that I wasn't convinced was actually therapeutic. We haven't done the listening therapy that our OT recommended for both kids, either, because it sounded like snake oil to me.

Good luck!