Speech delay in 3year old boy

Hello,

Please help me with some advise, I am so worried about my elder son.
Leon is 3 years and 5 months and we are on the waiting list for Asperger's/autism evaluation.

My main concern is his speech. We are bilingual family. Leon seemed to be developing normally up until about 3 years of age, he was evaluated at 2 and all was fine. He began saying his first words at about 18 months, by 2 he was putting 2 words together and by three he spoke in 3-4 words sentences. Now he would understand a command that would be delivered in a form of a long sentence and do what we ask him. Bu he seems to be lacking words to express himself and then get frustrated hit himself on the head sometimes. He does not have a concept of I/mine/you/yours, just calls himself by name, egg leon wants go to garden. He does not ask us ANY questions. He does not understand 'why' questions and some other more difficult questions like choice questions, when asked he would just repeat a question. He does answer simple questions though such as what is it? where is it?

he is shy and when in a group of children would normally play alongside them, concentrating on one specific toy. he keeps good eye contact, has a very good memory knows his ABC and counts to 10. He is attached to us, likes being cuddled. He is willful and gets frunstrated rather easily. Does not have any repetitive or unusual movements, his motor skills are good. His physique is tall and wide chest.

He had his MMR at 12 months but all seemed well right after. My pregnancy with him went well, he was always a healthy child not prone to infections/viruses.

Hope to hear from you soon!