Autistic Or not?

Apart from N's speech development, i am also concern about his social skills. It seems he has two distinct personality in different social settings, at home with me and outside with any other strangers.

At home, he is like any other toddler. He responds to his name, maintains good eye contact with me and even make verbal requests to me. He also replies to my questions promptly and accurately. He also immitates me very well.

However, he becomes a totally different child with others. He completely ignores anyone who attempts to talk to him, avoids eye contact and appears to not know the answers to questions but in fact he knows very well. I get really disheartened seeing how one adult after another fail to get him to converse with them. Oddly, when i repeat their questions, he responds immediately! He behaves like people around him don't exist. However, I notice he is aware of his environment. For instance, today we had dinner with his grandparents. During which he didn't interact much with them nor looked excited seeing them (we only meet them a few times a year due to our locations), BUT he was able to tell me later that he had met "gong gong & por por & C" (grandpa & grandma and his cousin) when i asked him who we met for dinner. Also, in informal settings i.e play he will make eye contact with the adults. BUT when he is expected to converse or respond verbally, he avoids making eye contact.

I have had suspected that he was autistic but when at home, seeing how he communicates with me, i was sure he wasn't. And no, he doesn't display any other common signs such as repetitive actions, obsession with an object, hand flapping etc. I brought him for an assesment (for both his speech & social developments), the Dr, after reviewing him, didn't think N is on the spectrum for autisim, MUCH TO MY RELIEF. However, she also agrees that his social skills need some brushing up.

During the review, the Dr asked if N plays pretend at home and my answer was 'not quite'. Apparently, pretend play is a huge factor they use to determine if the child is normal. Because of this and her observation on N's social skills, she has set him for therapy. I went home feeling like a bad mother because, i rarely play pretend with N. The Dr pointed out that that could be why he doesn't pretend play. After the visit, i grabbed every opportunity possible to test N if he could pretend play with me. One time, i gave him a bowl and spoon and made him pretend that he was eating something. He pretended to feed himself and even pretended that he was eating noodle. He also pretended feeding me and my husband. SO, i guess that's a pass?

I don't know. I am feeling preplexed. WHy is N behaving like this? I came up with possible reasons. 1) Its the environment he is raised in. Most of the days, it's just me and him. He hardly have any playdates and almost zero chances to play with other toddlers. His classmates have dropped out or move to another time slot which means the class is made up of just him and the teacher. Hence, he doesn't quite know how to interact with anyone else except me & hub 2) Its his nature, his inborn personality. Alot of my husband's friends insist that N is very smiliar to my husband who also is quiet by nature. 3) There is something wrong in his development. 4) Perhaps he feels that people, other than me and hub, doesn't seem to understand what he is saying (rightly so because of his poor articulation) he thinks its a waste of time communicating with them. 5) all of the above.

One moment, i am confident that my son just needs time to develop on his own. But seeing how different he is when he's with other children, i am not so sure. N is going for therapy but, it's going to take time yet i want a definate answer now. I need help. Do you know of any toddlers who behave in the same way?