J.K.
My daughter had 15 words at 19 months. She didn't say her first word until she was 15 months old. I was concerned she had autism, too. She didn't consistently respond to her name either. I had her evaluated at 19 months and again at 30 months. Both times, she scored at least average in fine motor, gross motor, receptive language, expressive language, and cognitive development. In fact, at 30 months, the evaluation revealed she was beyond above average in cognitive development and above average in receptive and expressive language.
It'll come, just be patient. If you are truly concerned, have him evaluated by early intervention and keep an eye on it since it's good to detect these things early and get help ASAP, but don't jump to conclusions.