It would be hard for anyone to give you an answer without observing your child's behavior first hand. I would be inclined to accept the answers you have received about speech delay. My daughter did not speak at all until she was 4 or so, and then just to get a need met with single word utterances. She and her brother were inseparable and big brother took care of her needs... she did not have to talk much.
Now she is a high school math teacher with a masters degree on the way. I would say that strong, loving, attentive parenting, not TV, computers etc... keep them turned off will keep things moving along just fine.