If you're honestly concerned, call Early Childhood Intervention (or Infant & Toddler Intervention) for a free assessment of your child's speech level. They provide therapists that can come out to your home and they do play therapy to assess if he's on target --where he needs to be for his age.
I first noticed my son's speech delay around this same age as yours. Yes, I had many people tell me the same things the previous comments said... that my son will talk when he's ready; that he has no reason to talk since I anticipate his needs; that's he's just not a vocal kid; that he doesn't want to, etc etc. And that may be true. But we live a vocal society .... kids need to know how to communicate... and the sooner they learn these skills in a positive manner the better off they are for their future in communicating with others. I tried all the tricks... baby sign language (supposed to stimulate communication center in his brain and help them communicate faster...didn't make him want to talk... he just used it more as a crutch, an excuse not to talk, just to use sign language); i read to him all the time; i put him in Mother's Day Out so he'd be around more of his peers and older kids so he'd be peer-pressured to talk more. Didn't work.
Here my son is at 3 yrs old still not using full sentences when I can carry on a full conversation with his peers. At the most, he uses 2-3 word sentences -- and those are only a handful.
The problem will really come into play when your child has to communicate with his peers and other adults -- other than Mommy or Daddy. He may get extremely frustrated and they may get frustrated not knowing what he wants or needs. And really verbalizing his emotions and what he's learned is a socially positive way to build his confidence and to participate in class-like activities. I had teachers at the church nursery and his Mother's Day Out notice his speech delay ... just that he was missing out on participating in class circle time conversations.
So I take this very seriously ... it doesn't hurt nor cost anything to get an assessment. And if he qualifies for speech therapy (good until their 3rd bday) -- ECI provides it on a sliding scale based on income - very affordable. At 3 yrs of age, speech delayed kids can attend free ISD Early Childhood preschool, if they qualify after an assessment, which is where my son is going now - he just started this week. [I think Dallas ISD has a similar program... my son is going to Plano ISD] I figure, so what if he starts reciting monologues and sonnets tomorrow, at least i know I did everything in my power to help him and give him every opportunity available to us to help him succeed and not fall behind his peers. Speech delay, i've been told by speech pathologists, if ignored, can lead to other communication problems down the road, speech impediments, using other negatives ways to communicate rather than using their words, etc. etc. Why not give him a head start?
Just my opinion and experience with speech delay...
ECI's website: http://www.dars.state.tx.us/ecis/index.shtml
There are different programs in different counties or cities. Just call the 800 # to see which to contact for more specific info. Good luck!!