njgal...dont stress yourself too much about it. Has she achieved her other milestones in good time?
At almost 3 my daughter could not even talk. She had a vocab of about 10 words. Even those she used to whisper most of the time. I had taken her to a speech therapist, but it did no good. When she did start talking, we could not understand her well enough. She used to get pretty frustrated. So I started speech therapy again. After just 1 session, we traveled and somehow, she started pronouncing those words much better....although it suddenly happened after about 4-5 weeks. Even the speech therapist was surprised when we got back. I did a follow up 3-4 sessions just as a precaution. She used to get a list of sentences to stress the letters she could not pronounce properly. For ex Goo By..you keep saying Goo*d* Bye. Keep stressing on the D...make a game out of it...use different funny words...somehow you need to repeat it like a hundred or so times during the day. So make a sentence like Re*d* Sa*d* Bu*s* is waitin*g* in the schoo*l*
She will be fine :)