Hello all....
I have read all the posts pertaining to this topic and I have to say that my heart goes out to you parents dealing with your special children. Daisy, I am glad that your son is getting the help he needs. I also believe, based on you description of his behavior, that he is on the autism spectrum. I am glad he is responding to behavior intervention strategies and that you were able to get him a speech therapist. When children show signs of being autistic, their greatest chance of leading anything close to a "normal" life is when intervention is started an an early age, prefereably before they turn 8. That is why it is very important as parents to investigate any behavior that is "unusual" and be aware of the expected behavior at each age or milestone, and be concerned when our children are not exhibiting such behavior.
"Chowchow" based on your description of your children's behavior, I do not believe they are autistic. However, I am glad you are getting them some help with speech. Again, there could be a number of reasons for the delayed speech; especially for the younger child, who does not see the older sibling talk much and may just be emulating him/her. Do they have opportunities to interact with kids their age? Perhaps you can put them in a school/play group where they can see other children talking and interacting, and that may be all they need. I will stop here because my post is getting rather long