From your source: "Even though cervix penetration is not actually anatomically possible, cervical stimulation is, and this can be enjoyable for some women."
I'm actually willing to concede that cervical penetration is a theoretical possibility. Through daily sounding and dilation over a long period of time, you might be able to fit a penis. Even then, actually getting the penis through the cervix would be exceedingly difficult: The uterus isn't fixed in a vertical position, on the contrary, it'll usually be bent forward, backward or to the side. During sounding, it'll usually be stabilized by a speculum at minimum. That wouldn't be possible during intercourse, again making penile penetration of the cervix highly unlikely even if one was actively trying.
As for the changes after childbirth, they're not as pronounced as you seem to think. The external orifice might change from a pinpoint to a short slit, but otherwise the cervix isn't all that different. After all, one of its functions is to be able to keep a fetus in place more than once. Actual source: https://pubmed.ncbi.nlm.nih.gov/1597273/
To sum up, no woman should be worried about their cervix being penetrated during normal intercourse, regardless of how many children they've had or how big their partner was. I can't speak to what happened between you and your partner, but I guess all that matters is that you both found it enjoyable 😁
Kim Fupz Aakeson har jo også skrevet ubegribeligt mange bøger. Jeg kender kun hans børnebøger og er generelt stor fan. "Prinsessen der altid havde ret" er i fast rotation derhjemme.