What they don't tell you about postpartum is that you'll be fine, but you'll rip your hair out. And then it'll fall out. Massively. Every time you run a brush through it, there will be wads of hair. The thinner it gets, the more tangled it gets.
You will not sleep, even if your baby sleeps through the night. You will wake for every whimper, every grunt, every little noise... but only the important ones.
You'll always be starving, but you'll never have time nor want to eat, because you're supposed to lose weight from breastfeeding, right? Wrong! Not unless you starve!
You will love and hate everything all at once, and you will cry. A lot. Nonstop. Over everything from cluster feeding to sleep regressions to losing your hair to being hungry to just wanting attention that you constantly get but you need more. You feel like your SO has abandoned you with the baby but he needs his space too. But make him help. Don't do it alone if you don't have to.
Yes, you're going to get HORRIBLE advice from other people, mostly old lady moms who don't know what the heck a "social media" or a "bumbo" or a "boppy" is. You'll hear "well with so-and-so I did this and he/she turned out fine!" more times than you could ever possibly imagine. But do you, mama. Don't let others try to run you over.
Yes, you will go a few days without showering just so you can get more sleep. That's okay. That's okay for your baby, too. I promise your baby will sleep all night someday. She will eat less than four bajillion times a day, someday. Someday he will let go of your hand while you're trying to get things done. Someday they will be independent people.
And that is when you will sit down and cry some more.
You can be frustrated, sad, anxious, whatever... but cherish it.