N.,
You don't say if you think he is reading at level, but you have raised enough red flags to need evaluation. I am an educational advocate, and very soon, your son will no longer be learning to read and write, he will be reading and writing to learn, so it is imperative that you identify what the issue is now, get him the help that he needs, and put him on the road to success. Write a letter to your school and ask for an evaluation to determine if he has a learning disability, or executive dysfunction. Ask them to give you an answer in writing and do not let them talk you out of it.
At the same time, get a private educational evaluation, one that you own and control, from a psychologist, developmental pediatrician, neruopsycholgist, or a licensed School psychologist. You should never go into a school meeting knowing less than the school does.
This could also be a visual problem, and I would recommend that you call the occupational therapy department of your local children's hospital and ask for them to give you then name of a developmental optometrist in your area. This kind of eye doctor not only measures visual acuity, but also measures how well the muscles needed to read well have developed.
I wish you well, don't wait, this problem is probably not behavioral, and it will not just go away all by itself. It sounds VERY familiar. Find out for sure from professionals, and then do everything you can to get him what ever he needs as soon as you can.
M.