OT has said SPD. Nursery and school say he is fine and I think SALT is going to say that too (she gets to decide if we get on the ASC pathway).
I have read things that say SPD can affect eg social skills basically because they are so focused on their sensory stuff that they don't have time/energy to develop socially. Might be the case for some children but I don't buy it for ds.
This is my list. Any of these explained away by SPD? Can anyone add any more?
Literal thinking. SALT said when he was told to colour the back of his house (ie part of a picture), he turned over the piece of paper and said there was nothing on the back.
Doesn't get jokes. He gets upset as to him you are saying the wrong thing and it doesn't make sense.
need for routine gets more difficult to handle as a result of changes - this is always put down to my parenting as triggers aren't obvious.
rituals and rules
struggles with some transition But he is masking at school and falling apart with me at home in private.
obsessions unusual ones in the past but now is something typical for 5yo
repetitive singing, phrases
toileting issues won't go as he is worried about scary thoughts coming into his head 
social issues Doesn't know how to join in a game, doesn't say hi/bye. I am working on these with him and nurturing friendships with schoolmates so I think professionals won't see this stuff.