With regards to modernity, I think specifically we are in a time where it is both much easier to not have a child, while also much more difficult to raise a child because of relative economic and social pressures of this period. My peer group mostly mirrors yours in that all but one are childless, with most not looking to have children at all.

There are many birth control options and views on abortion have changed significantly as well as education which has improved, which means much fewer people keep unplanned pregnancies. Simultaneously, working and middle classes in western developed nations have continuously been squeezed within our the lifetimes of people who should be settling down, 2 severe economic contractions combined with the pandemic on top of preexisting job, wage and other social insecurities makes the financial and social burden of having a child much more difficult to bear.