Speech Delay

My 32 Months old son can be so sweet and loving one minute and then if he is told to do something he does not want to do he Cry, yell, and throw things (his toys)
We notice that other people don’t understand him when he is talking, so we get him speech evaluated, and he will start his speech sessions next week
He was attached to his nanny so much (to the limit that he would think she’s his mum) and she had to leave couple of months ago to visit her family, and since then I notice that he would avoid sometimes eye contact, also 60% of the time he don’t answer me if I call him and he is busy playing with his favorite train, his hearing test was normal as well
Also we are speaking 2 language in our house and my son was never in kindergarten and his exposure to group plays is extremely limited (my mistake), however he play very well withhis older sisters (7 years and 41/2 years old)
Do you think I should go for full developmental behavioral evaluation? And if yes where is the best place to do so, also I was trying the Children memorial Hospital and I was told that the first availability will be next year, and I understand very well that few  weeks if  treatment needed means a lot and the earlier the better
Your feedback is highly appreciated
Thanks