Your claim that total fertility rate being sub replacement rate mostly due to biological inability to have children is not seen in any data I have seen.

All the trends correspond directly to women’s emancipation (although men also probably want fewer children).

I am well aware that this is not a mainstream view (yet), but the rate of decline in fertility in the past 20 years is not something that can be explained through social changes alone. Even in Afghanistan fertility has taken a nosedive and the social situation for women there has definitely not improved.