@sebe I've been doing somewhat regular therapy and I've been on lexapro since coming home from the hospital (delivery). It's helped heaps.
It's not an independence / confidence / PPA thing. It's more of a thing about whether we legit can afford a second kid without decimating our cash position beyond repair, and whether I can endure a few more years of infant hell before the kids are old enough to feed and poop by themselves and sleep through the night.
I had to make the tough decision to "retire" from "competitive" running (i.e. entering into, training for road races - I put those in air quotes since I'm by no means a pro; just someone who is fast enough to podium in her age group) because my partner was struggling too much to care for our son alone on Sunday mornings. And forget about writing, since my writing group meets for like 2 hours on Wednesday evenings once a month. Because we don't have evening care, I can't join that.
My only child experience: I just felt very isolated and otherized. Didn't really have friends in middle / high school. I remember having friends in elementary school but those were more like playmates. Was bullied in college (sorority girls called me a slut, etc; I felt like I was on the outside looking in). Being an only child forced me to get out of my comfort zone, put myself out there to make friends. I then moved abroad and to a ton of different cities (trauma response - hyperindependence) and eventually formed a TREMENDOUS circle of true friends and acquaintances, but that wasn't until my 30s.
If I had a close r'ship with a sibling, I would have been like my dad - didn't need to make friends bc his siblings were his friends. Never moved far from them, never would have moved abroad, never would have chosen a city other than the closest large city to home.
I have no idea how to make my child's life better if he ends up an only child. The go-to response is COUSINS but since we're estranged from my husband's sister (who doesn't want kids), my son won't have the opportunity for cousins. I remember that the only time children really talked to me as a kid was when I played with my cousins and seeing them more would have made my young life more enriching, but my dad had to move away from his long time family home for a job.