I agree that it would not hurt to have your baby checked out at to doctor.
But it is my belief that all babies progress at their own rates. I have been through five myself. I had one who was very slow to walk. She didn't really walk until she was almost 2. Another I could not potty train until nearly age 4!!!
I would also make sure that I was reading to my baby as often as possible, I think it's important for them to engage in language as much as possible, especially if you think they're falling behind.