Dear A.,
This is going to sound bizarre, but I recommend taking a careful look at your daughter's diet. I say this because I had a lot of concerns about my son's speech -- basically from one year to two-and-a-half. I expressed this concern to several of the pediatricians in the practice he goes to, to an ENT, to an audiologist, and to a speech therapist affiliated with Early Intervention. I know this makes me sound like a crazy worry-wart of a mom, but my son's speech was VERY unclear and his vocabulary was very small and developed very slowly. All those people told me he was fine. But it was just clear to me, observing my son, that something was up. I finally consulted with a naturopathic physician, really because of concerns about my son's digestion. She told me it sounded like he still had a significant milk protein intolerance (which, BTW, cannot be detected by an allergist's pinprick test) and that that was producing congestion in his ears. She recommended I get all traces of milk out of his diet, which means reading all labels like a hawk. Within two days, my son's speech just took off. I mean, the change was so profound it felt like science fiction. Within a week, his articulation was about 500% clearer. Within about three weeks, he had begun to speak in long, complex sentences. Now, at 2.7, my son's speech is way ahead of his age group.
I don't know if your daughter has any of the same issues, but naturopaths are trained to be sensitive to things that register as the low end of normal on most charts and to look for natural, non-invasive solutions.
Best of luck,
Mira