Middle Earth-Musings on Elven Population and Birth rate

So I woke up this morning in one of those strange brain moods pondering random things. Finally my semi-conscious thoughts settled on Tolkien. The numbers are pretty hard to make work

There were 144 Initial elves sometime in the middle of the first age. Then after a bit of time they were called to Valinor. Many others died in the Journey or ended up going to Valinor. Then some came back, and other stuff happened blah blah.

But their birth rate is absolutely paltry. They live for thousands of years, but seem to generally have 1-3 kids in their lives, with dudes like Feanor an exception with 7(but he was an exception in all things really). And It’s not like they all turn 16 and pop out their spawn, They have them after living a lot of years.

So either those first Elves were humping like bunnies/had much higher Fertility, or the First age must have been half a million years or so to account for the Numbers of Elves we seem to see.

I think there might be cultural differences in play. High elves (and almost-high elves like Elrond and Thingol) are the ones who seem to have very few children, but most of the elves we see in Middle Earth are wood elves. Perhaps they never learned the moderation of the High Elves, and have indeed been humping like bunnies.

Useful link for this topic: A cross-referenced list of everything Tolkien said about elf sex

My own Extremely Authoritative take on it.

Tolkien deliberately never said how long the first age was. It could have been a million years.