My hats off to any woman who can spend all those years just being pregnant and raising babies/young children - physically as well as mentally shattering!
I have 4 young children and it is hard work. I also agree with Riven that it is a GOOD thing that children take SOME responsibilities for household and younger siblings - although not at the expense of their own wellbeing, of course.
Even with my 4, they don't get as much one to one time with a parent but they do love being with each other (even though they do fight of course!) and learn a lot from each other too. TBH most of the time it's a spontaneous thing - like DD1 now reads bed time stories to DS1 as she wants to, we've never asked her to or expect to.
I would have loved to have a larger family, but finances and age didn't allow for it. But I am not sure I would have gone for 18...maybe 6 though :o)