Hi there. Let me ask you a question about her other motor skills---- especially fine motor skills? Just curious as she may have some motor planning issues. My son has motor planning issues and it involved speech as well as other things.
Speech has three parts to it------ receptive (does she understand what others say to her), expressive (can she formulate responses) and articulation (actually saying the words clearly, making proper sounds). To speak it takes great coordination of many things including executive function/motor planning. You can think of this as the way the brain organizes itself and then sends the message via the nerves to the mouth to say something.
So, does she follow any comands you give her? Does she point for things? Does she understand YOU? Very important.
If you are already working through the school's early intervention preschool program, I'd ask for a FULL evaluation including occupational therapy. They work extensively on motor planning as well as other things that a child needs to be successful. This would be great to add to speech.
I've also talked to many people as of late and while the school system is good, if you can have your insurance pay for any private therapy---- that would be great to add. I know it is very hard to get speech covered by many policies but perhaps you can get the OT added. Also, if you feel that your school is not providing quite what your daughter needs, stay very positive with the school but also consider adding an advocate to your team. Schools do not love this as an advocate will fight for MORE of what your daughter needs. If she has speech once or twice a week, she'll maybe get it daily. Does she attend an intervention preschool by the way? If not, I'd strongly suggest that.
One thing our school does for a child with apraxia that DOES understand is to teach them sign language. It does not stop them from speaking and actually encourages them to do so. That increased ability to communicate helps them focus on speaking rather than frustration of not being understood.
Bringing me back to my initial question, how are the other two areas of speech for her---- receptive and expressive?
Have you had Auditory tests to make sure she is hearing okay ,here is a link for more information www.speechdelay.com/milestones
Yes speech therapy is the way to go, perhaps get her a therapist that isnt school related .Have you spoken to her pediatrician about it ?