It looks like your school uses the big, bad DRA. The DRA is notorious in dyslexia circles because it's a test and reading instruction system that relies on sight words. A dyslexic child with a solid memory can limp along for quite a ways before showing to the teacher that there's a problem. Indeed, my daughter would never have been uncovered as having reading problems using DRA, and it was not until I took her for a private evaluation did we have a diagnosis.
Further, if 12 is his independent level, then he passed that level, and the teacher should have kept assessing to find his instructional level. It sounds like that wasn't done. If you are to monitor his actual progress, then you need the teacher to find the level at which he makes errors, reads too slowly, or cannot understand the story. And then you need to look at the nature of errors that led to not passing the level. Be aware that at 18, there begin to be non-fiction texts in the assessment, and a child who has brute-forced reading through sight word may show a big difference in reading accuracy between the fiction and non-fiction versions of the test at that level due to more unfamiliar words.
Finally, have you sent the school a request to evaluate? If not, it's not clear to me that the special ed teacher will get back to you. In your place, I'd request tha t the teacher evaluate up to his ceiling on the DRA and ask the school to administer either AIMSweb or DIBELS as an initial screening for dyslexia.
