Re: speech disorders
One of my mom's cousin has two toddlers, who were born pre-maturely, who did not begin speaking AT ALL when a todd is supposed to do so. So, everyone said that some kids speak a bit late and there is nothing to fret about. Some time passed but they still didn't speak and then people said it could be because they were pre-mature children so just wait a little more. Some more time passed and then he took them to doc. Doc got them a speech therapist and after about 2 years, his first born has started uttering words like Yes, No, Nothing etc. She still doesn't talk much and definitely doesn't speak in sentences but still she has made a very good progress. Seeing his big sister, uncle's second born seems to be doing better on words too.
Going back to your original question, which was about the signs of speech disorders, in this case there was nothing really to point on except the delayed speech. Uncle's first born would understand EVERYTHING and if wanted someone to understand her point, she would nod, shake her head, point to whatever she wanted etc. and if one couldn't understand her, then she would start crying...She goes to school now and is doing very well there MASHALLAH...