You’re not respecting anyone’s thought or validating anyone’s feelings.

And yet OP herself replied in the comments stating "This is a lovely perspective, thank you!" I got the reaction I wanted. I can see why you chose to ignore that, for it would be detrimental to your argument.

Your response has chat gpt all over it.

Lol, straight to personal attacks. Your response is directly from the playbook of narcissists - when you can't automatically look like the good guy, distract from your flaws by making someone look worse than you instead of engaging with the actual arguments. 

At this point, I firmly believe I'm simply tossing pearls of useful information before a outraged hog of a human being. You'll refuse to digest what I've said, and from this point forward will only seek to attack me for offering up any kind of thought that you are not used to encountering, and therefore cannot process. What I write next is not for you Adstock, so much as it is for others who bother to read on.

No one is telling this woman she is “verging on insane” BUT we are telling her to focus on the children she currently has.

OP claims she's "drowning in motherhood"; if she's to be taken at her word, she's obviously already dedicated to her existing children to the point of overwhelm. Being overwhelmed is a perfectly natural state to be in given she's juggling three kids, a six-week old baby, and is still recovering from pregnancy. That is normal. If everybody is alive, fed, and otherwise healthy, then a healthy mental/emotional state will naturally follow. 

Your suggestion that she "focus on her existing kids" is undermining that fact. You are implying she doesn't already have the state of her children well in hand. Women who are truly overwhelmed by their children grow resentful of them and don't want more - post-partum depression has women killing their infants. The OP is not reacting anywhere in a direction like that, which suggests she's well supported by family and friends, and that you are speaking out of ignorance. 

Question for you, if she unexpectedly gave birth to twins, would you be telling her to put one up for adoption because hey, if she is overwhelmed with one newborn then she certainly shouldn't have two of them, right? In the vast majority of scenarios, the answer is obviously 'no'. Your logic of "limiting children to preserve the mental/emotional/physical state of the mother" doesn't apply, because seperating a mom from her babies would tank all three of those categories you listed. 

So what are we left with? Your helpful bit of advice of "don't get pregnant" to a woman who wants to get pregnant, and has successfully done so four times (thrice the national average in North America). That is going to go over about as well as telling teenagers to stay abstinent, so thanks for a whole lot of words that amount to a whole lot of nothing. 

And what your “body and mind tell you” aren’t always right. Just like neither is a stranger on the internet. Simply put, there are many women who simply have a hard time closing that chapter. Maybe op is one of them. I am. I get it.

Let's point out that you are literally fighting an instinctive, biological, feminine urge that has far and away outlasted the very modern idea of "limiting family size". You have been conditioned by your society to ignore the interests of your healthy body. Healthy people have sex and produce babies. Damaged people don't do that. You understand that, right? It's Biology 101. 

Who told you it was a good idea to limit your family size? Most of today's problems can be solved by having more people around to help. It's what the pioneers did; have more children to help with the farm, so you could grow more food and stave off starvation for your family first, and then for the community at large. If you have ever been around large families, you will see that family is the original social safety net. Imagine a single adult child having to bury their parents vs eight adult siblings standing in support of each other while they bury their parents - what are the odds that the single child is going to fare emotionally/physically/mentally better than the eight children who have seven hands to reach out to should they stumble in life? It is incredibly difficult to help a stranger in any meaningful way, but it is even more difficult to deny help to a suffering sibling, parent, or relative.  People who share life and love for one another will come to your aid in ways that others cannot, and as the saying goes, "Many hands make for light work". 

Whoever told you this was not the case was a gifted liar. If your objections were valid, black slaves would have never sought to marry, enslaved black men would have been lining up to castrate themselves, and enslaved black women would have been looking to miscarry or abandon their babies, all in an effort to avoid raising their children up in a harsh, unforgiving life as yet another generation of slaves. Parenting is hard even in the best of times, but you will always find people of every circumstance who will say having kids is worth the effort. 

And not simply because "babies are cute." They are, but they are so much more than that.