Sounds like you got the same advice from your Pediatrician that I did when my son turned two and wasn't talking. The thing is, your little man has two things going against him in the speech department. One, he's a boy. In general, boys just seem to talk a little later than girls (and a lot less...which is usually true in adulthood as well). Secondly, I saw from your profile that he's your only child. He's literally the pioneer baby in your home, being the first to experience EVERYTHING. Because of this, he doesn't have any older siblings teaching him the ropes...and teaching him to talk earlier. For some reason, kids learn a lot more from each other than they do from us parents. That can be a really good thing and (at times) a really bad thing.
Like I said, my son was in the same situation by his second b-day, and since he was our first, we freaked out a little. Will he EVER talk?!! Is something wrong with him? Well, I'm happy to report that my now three and a half year old boy will NOT shut-up. In fact, the more his speech develops, the more eager he is to share ALL of his opinions. Specifically what he doesn't agree with and how, exactly, he wants to spend his time. ;-) Seriously though, his sentences are long and complex and getting more so every day. It's a little mind-blowing, actually.
My daughter will be turning two at the end of this month and she has been talking well for quite a while now. I KNOW she's learning from Luke because she uses all of his little special words (and pronunciations) for things. Of course, she's also a girl, so she practically came out of the womb talking. :-)
Anyhow, you should try not to worry about it...though I know it's hard. Sometime in the next year, your son will have a language EXPLOSION. Seriously, you'll feel like it happened over night. I think my son's came at about two and a half. So hang in there and enjoy the silence (and the lack of attitude) while it lasts!