how many words should a baby be saying at 16 months?

I know every baby is different and hit milestones at different ages, but ballpark range, about how many words should a 16 month old be saying? I’m starting to get a little worried, my son only says hi and dada on a daily bases, he says what’s /who’s that SOMETIMES, and has said said oh shit a couple times (🙄🙃)

he hasn’t even said mama yet, he makes no attempt to say real words no matter how much I talk and try to get him to, I read multiple books a day and try to explain whatever i’m doing.

is this normal? should I get him into speech therapy in a few months??