My oldest son (now 9.5) had some speech and OT issues and I went through the state when he was 2 and then onto the school system when he was 3. Now that your daughter is 3 you must go through the school system for free assistance. Call the Administration Office of D158.
There is a woman named Jennifer Korn who I believe works with D158. My son went to her "school" prior to being 3. I saw her recently at an elementary school in Woodstock and she told me she now works for the Huntley School District (I think that is D158 also). I think she is fabulous and was very good at working with my son and me. My son still remembers the school and where it was in Crystal Lake.
Just keep an open mind and get as much input from as many people as you feel necessary. She is your child and you know her best!