Talk to Pediatrician on Child Development

I need an evaluation for my 15-month-old baby boy. He cannot stand alone or walk yet, but he pulls up and stands while holding onto things. He does not say mama or dada, only makes babbling sounds like "dadadada," and he does not answer to his name unless we call him in a loving, sing-song voice. He also does not point with his finger, wave bye-bye, clap, or shake his head for yes or no. On the other hand, he copies us during play: he slaps the mattress back and forth when his grandfather slaps it, moves his head fast when I shake my head.

Is there cause for concern or should we wait and see?