16 month old walking/talking

Our little guy is about 16.5 months old and he's still not walking or talking. He'll walk (or run) with his hands being held but drop his butt down right as soon as you let go of his hands. He'll walk around all sorts of furniture, but nothing on his own just yet.

Then when he talks its the usual "Mom, dad, dog, hi, Chuck (Our dog), hi, yeah. That kinda stuff and tons of babble. Its all pretty simple stuff. Totally seems to understand us when we ask "Are you hungry?" "Grab your book". So he seems to be learning what we're saying but not really saying it back too much.

Am I just overthinking everything?