Follow the above advise. A Speech Therapist is responsible for speech and language development as well as social interaction and play skills. You would be wanting one that has experience of speech delays associated with hearing loss, as well as developmental issues.
If you also google to find similar characteristics between those on the autistic spectrum and those with hearing difficulties you will see that there are some similar difficulties. But those with only hearing loss do go on to learn the skills that those on the spectrum always have difficulty with (however children on the spectrum can be affected in this, or any area, severely or mildly). This is just my own opinion, but the reason I think that the two types of children develop similar speech and social characteristics is because many on the autistic spectrum have language processing difficulties to such an extent that they are getting about the same amount of auditory information as a child with hearing difficulties. So although they aren't deaf and can 'hear' they can't actually process alot of what is said at the time it is being said, which maybe similar to how some children with hearing difficulties pick up certain aspects of a word or a sentence, but maybe not enough of it to get the full picture.
So get him into a programme with an experienced SALT as above and ask them to also teach you how to communicate with him and also how to interact socially.
Your post is showing that he is showing an interest in other people eg. asking where mummy is, and he is also wanting to interact eg. asking if you want to go outside with him. Children on the spectrum tend to come across as very self sufficient and don't tend to seek interaction and play to the extent that their peers do. Many can be quite content in their own company for most of the day or they can go to the other extreme and always want someone with them, but only to follow their instructions or meet the child's needs eg. I want a drink, I'm hungry, turn on the TV, and not interacting and chatting with them as other children do.
But I would also mention to the SALT about characteristics similar in children with autism and hearing difficulties so that she can explain that to you.
If you persist in having these concerns then you can ask for your child to have a full assessment by a team of professionals that are experienced in diagnosing autistic spectrum disorders in children who also have hearing difficulties.
I would definitely recommend that you have your son's speech evaluated and seek early intervention services to target his language delay. Your pediatrician should be able to assist with identifying some local resources for developmental screening. Aside from your language concerns, the other issues that you describe sound fairly typical for a toddler, but you should describe all of your concerns during an in-person evaluation.