Im the speech therapist that posted before on the speech therapy and autism topic. its great that your little guy is pointing and interacting, but i would recommend getting a speech evaluation. we recommend that 18 month olds have at least 15 words at an absolute minimum. while some kids are just late boomers and may grow into speech, often times a speech therapist can tell if its something they will grow into or if something is standing in their way, preventing them from talking. early intervention is the most important factor is a child's success in speech therapy. its better to do therapy now when they are only 4 to 6 months behind instead if waiting till they are 2 or 3 and are a year or so behind. the language burst typically happens between 18 to 30 months and you don't want to miss out on that happening. let me know if you have any questions, id be happy to answer them.
If the language burst happens between 18 and 30 months, why would you run in at the beginning of that window?
You're the professional, so I'm not contradicting you, but it seems kind of alarmist to me.
To the OP, I do have a co-worker who is taking his 18 month old to early intervention speech therapy because his daughter also has no real words. She's adopted and was exposed to drugs in-utero, so they are erring on the side of caution with everything. Anyway, once they got into the speech therapy, they learned that she actually did have some words that they weren't identifying because they were listening for obvious, fully-formed words, but the therapists were able to identify sounds that their LO was using consistently to identify different things.