My 21 month old son isn't really saying much except mama and I'm not sure he even really knows what he's saying when he says that. He uses a pacifier for naps and bedtime but he's been climbing to get them during the day too. There is no real regression in speech since he never talked much at all, what I'm worried about is his cognitive skills. If I ask for a kiss sometimes he'll do it and sometimes he won't, if I call him sometimes he looks and sometimes he doesn't. He doesn't stim, no stacking or spinning or lining up toys. He doesn't arm flap or use repetitive behavior. Could this be autism or some kind of retardation? He's very happy otherwise.