Is he going to be re-evaluated in the not-to-distant future? What does his pediatrician say about all of this?
Just from the information you are giving about the pre-k program he is in, he might qualify for coverage under the Individuals with Disabilities Education Act. This means that once he gets to kindergarten you and your wife work with his teachers and therapists (speech, etc.) to establish an Individualized Education Plan (IEP). An IEP helps teachers understand the special needs of a child with a learning disability. So at the very least, you can relax a bit knowing that your teacher understands your child has different needs from other kids in the class and might not necessarily be "on the same page" as everyone else.
Anyway - hang in there. A lot of times kids just take a while to pull it all together. I am still having issues as an adult.