L.H.
Hi L.,
I'm in the speech pathology program at CSUN where they also have an early intervention clinic for 0-3 year olds. I am NOT a speech therapists, so please do not take my advise as such.
What I can tell you is that your son's age he should have about 20-25 words that he uses frequently. If you are able, place a paper and pen on your kitchen table, or a few around the house. When you hear him say a word write it down. You can put tally marks by the ones he uses more than once. At the end of the day add up the words he used during the day. (Only count each word once.) Do this for a few days to get an average, but the first day should give you a pretty good picture. This will tell you where he is at.
To elicit words, provide him with lots of opportunities. If he points to something, ask him "Do you want the book?" If he nods yes then pretend to be silly and not know what he means. Something like
"Oh-oh, mommy doesn't know what you meant, I'm going to guess that you meant yes? (he nods) Tell me yes."
Give him time to respond. Rushing through responses and answering for him takes away the chance for him to process the information and to formulate what he wants to say. (Don't worry it will speed up before you know it, but go slow for now.)
After you two agree that he wants the desired object, say a book, then expand further.
"This book? You wanted the book? The book called The Very Hungry Caterpillar? Can you say/tell me "book"? (pause and prompt again if he doesn't -say "book".) When he says the targeted word make a big deal about it "Yeay, that's right this is a book, here you go." Don't worry about correct articulation, just get him to start having more output.
As he starts using more words he will be less frustrated. I think it's okay to let him be a little bit frustrated as it will give him some motivation. Now mind you, I don't mean that you should just let him be frustrated, but offer the tools he needs to solve his problems. A lot of this you already do in different areas: you have shown him how to put on clothes, eat and drink by doing it every day.
You have to talk a lot, but you also have to give him the time and opportunity to speak. Don't give into his gestures for requesting right away.
Good luck!
L.