I'm really liking where you are going with this Arif.
Keep it up.
As far as conveying a sense of urban orphan there are some refinements you might push in the current drawing but the pose is really telling the tale. Without more context (or a pose to suggest a particular emotion) its reading as the child happily walking somewhere.
Currently he has a satisfied (not a care in the world) look. The clothes are unspoiled, crisp and untattered and there seems to be a spring in his step. Its as if someone just gave him something to eat and a new coat and hat as a present.
The mouse's face echos that feeling of satisfaction.