Visual recognition of letters is a very different skill to those used in spoken language and auditory memory so her strength in one area does not predict or necessitate strength in another. Whilst I'm certainly not an expert, I'd say 3.5 is too early to be considering a dyslexia diagnosis, and that this age, it's normal for her to not be recognizing letters.

Sorry to be short and sharp. BF while typing. Try not to stress Hun, but of course, if you do feel there's really more to it, see a Pead or Speechie.