I would explain to the psychologist exactly what you described in your post. I would think she would be happy to help you understand your son's strengths and weaknesses and how to help him with reading.
If you suspect a learning problem, I think the sooner you find out what's going on, the better. Then you will have time to help him before he gets too behind.
I think it's a crime that schools wait until children are failing to give them services, but maybe there are things you can do for him outside of school.
