I agree with filz, he sounds completely normal. I spoke with a friend of mine who is a Speech and Language therapist about my dd. She was nearly 2 and had a few single words like "oof" for dog, mumma, baba (daddy), jeesh (breadstick) and basically other sounds which we knew represented certain words.
My friend said that as long as she obviously understands what you're saying, and is starting to follow simple instructions/requests like "where's your nose", then there shouldn't be anything to worry about.
She was absolutely right - at 2yrs and 1 month, dd started speaking in full sentences! She never shuts up now
The advice I was given is not to ask questions, but to comment on what you and your ds are doing.
E.g. oh yes ds, you're pushing the car.
You're eating your pasta very quickly.
Just keep giving everything a name: car, doll, bread, cooker, window etc.