Hi L.,
I would immediately contact the school and the local health department to start your daughter in a speech therapy program. She will probably be pulled out of her normal class for about an hour a day while she is in school to continue the therapy. For your younger children the local department of health usually offers developmental screenings, which can identify problems sooner and start the resolution sooner. Like immunizations the rule of thumb is 1 screening before 2 years old.
If you are in the SLC area I've listed below some infto for Jordan Child Development Center.
http://web.jordan.k12.ut.us/jcdc/development.htm
7501 S. 1000 E. | Midvale, UT 84047 | ###-###-#### | Chris Giacovelli, Director
My brother was in speech therapy as a child and is very normal and very successful in his career today. So don't get too blue, just get her the help and support her in all the ways a great mom like you can.
Kind Regards,
TRUDI