Hi, Don't worry about this, boy normally start to talk very late compare to a baby girl. They don't talk well doesn't mean they do not know what they've learn so far. He will amaze you once he start to talk...

Since you are a working mum, you can let him join some weekend enrichment class or playgroup class on weekend. There are few playgroup class ogarnised by church are free or with very mininum charges. So he will have chance to socialise with other children.