I would be interested in finding out what is actually happening in class since the teacher gives one account and your DS gives another. Any chance that a counselor or other support person could observe a typical morning/reading lesson and report observations? IS your DS working well or not? What are his difficulties? That way you have some accurate info from someone who is really watching him, not someone trying to teach x number of squirming 6 year olds.
How much labor does it take your DS to produce his nice-looking writing? His extreme reluctance to write is certainly a red flag for dysgraphia. Dysgraphic kids can sometimes write beautiful letters but this takes an inordinate amount of time.
My DS is dysgraphic and had every excuse in the book not to write at that age. He is a negotiator so I interpreted his writing reluctance as strong will. He didn't get diagnosed until 4th grade because writing avoidance and phonetic spelling are "normal" for quite a while. The spelling you describe is normal for a 1st grader but if he is dysgraphic it will never improve beyond that.
Hopefully your DS has no writing disability but strong willed, intelligent kids can hide it and compensate for quite a while. I really wish DS has been diagnosed in 1st grade!
If you can really rule out ADHD his "lack of focus" could be just task avoidance. He may or may not have anything going on LD-wise but task avoidance in general is a red flag for something. It could be a visual or fine motor challenge as previously suggested also.
