OMG S., I'm right with you...
Our 19m/o son doesn't talk at all. No words. Period. He grunts, hums, "sings", just started pointing, but no words. Everything you described about your kid is exactly our kid, too.
We teach our son Sign Language and thought that that may be a contributing factor to his delay. We've had him evaluated by Early On and they said that he comprehends at a 22m/o's level, but expresses at a 16m/o's level. Not enough to officially call it a "delay", but we're enrolled in a S. playgroup-type class to help stimulate him. Personally I think he's just not ready to talk, but I got so tired of his pediatrician having a coniption at every checkup since he was 6m/o because he wasn't talking. Besides, it's free to participate in Early On and it shut the pediatrician up. :)
One thing I didn't like about Early On - They suggested we stop teaching Sign Language, and they suggested we stop talking to our kid in complete sentences, but instead talk to him in two or three word sentences. But he understands and is very bright, and I think that's because we talk to him the way we do and we read to him so much.
So good luck with your little one. :) I know it can be frustrating, but hang in there. Get him evaluated by Early On, it's better to be safe than sorry, and it's free.