It says in Torah that Hashem said to Avraham Rabeinu that his progeny would be without number—but you can pretty much count how many Jews are in the world. What don’t I understand?

Hasham said that there would be progeny like the sands on the beach, stars in the sky—uncountable–so many. But there’s about 15 million Jews in the world. We know it’s less than one percent of the human population. So what’s going to happen? What am I missing?