Even I have the same question..My son also 3 years old.. having speech issues.. Can anyone help us..
I am not exactly sure about the situation on pdd..but I would suggest talk to your son in which language he is picking up fast because first he need to learn to express his feelings to you.
Later you can slowly teach him English.
I have a 2 and half yr old baby.. I always used to talk with her in Kannada (common language spoken between me and my husband).
My mom is from andhra (she only know telugu) and she speaks with her in telugu, initially my baby had difficulty understanding telugu later on a daily bases she learnt but the first language she learnt was Kannada as that is wat we communicate at home the most.
Thanks so much Anjali17. Like you said,i will continue talking to him in his mother tongue in which he is picking up fast. Once he is good, i think making him understand english will be easier. In the meanwhile, i keep adding couple of basic english words and sentences so that he slowly understands English too.