"You should have another one," a woman - a stranger - says to me at an event last week, as I tell her about my seven-year-old son. "He'll be lonely."
The words sting, then burn.
My head is full of champagne and the room is crowded, so I smile, a weary, polite, reflex of a smile. "Maybe," I mumble. "We'll see."
But she doesn't stop.
"You're still young!" she tells me. "You should have another."
There's a pause. "So he's not lonely."
I take another swig of champagne. "Why don't you mind your own business and not tell me what to do with my bloody uterus," I respond.
Except, I don't. Do I.
Instead, I feel the familiar pin pricks of guilt, the feelings that arise whenever the "only child" question comes up. My mood deflates and with it my heart. For this isn't an isolated incident - it happens, often. And I am tired, so very tired of it.
What I want to say is this:
I don't need to be told that my son might be lonely if I don't have another baby, because I think about, worry about it, reflect on it, and am reminded of it every single day.
I worry about it when I pick him up from school, where most of the mums have babies strapped to their chests or snug in prams.
I thought about it, last week, when I watched two young sisters, hugging after ballet class in their matching pink outfits and my heart threatened to burst.
I think about it when I see siblings arguing in the park, fighting over toys or who pushed whom - a stark reminder that sibling rivalry isn't there, doesn't exist, in my house.
It's on my mind when a message pops up in the sibling group chat I have with my two younger brothers and younger sister. My goodness they drove me crazy when we were kids, but I don't know who'd I be without them today.
I reflect on it when new research comes out about only children, or when I read articles about adults who didn't have - but longed for - siblings.
I think about it when my son, very occasionally, asks if - no, when - he's getting a younger brother or sister.
And, most heart-breakingly, when he tells me, himself, that he gets lonely sometimes.
I do not need you to tell me.
There are so many reasons why people choose not to have a second child - reasons, and context, a stranger simply doesn't have. For some parents it's a financial decision, while others battle infertility. And then, there are people like me, who suffered from severe perinatal mental health issues, and don't think they can go through it again.
Becoming a mother almost killed me - there's no way to sugarcoat that. Postnatal psychosis tore my mind apart, leaving me aching to die at the same time as I welcomed a brand new life. The cruelty of it, of this maddening juxtaposition, still makes me want to weep for all I lost to this frightening, horrific, time. The trauma is softer now. It's not as raw and sharp, and it doesn't engulf me when triggers threaten to pull me under.
But let me be clear: it's taken seven years to get to this point. This health, this happiness, is hard-fought. And I don't want to, can't risk, losing it again.
I am here, alive, well - and mother to a little boy whose resilience and humour and intelligence takes my breath away. He needs me more than he needs a sibling.
So, with respect: back off.
Lifeline 13 11 14.
PANDA Helpline 1300 726 306, (Monday to Friday 9am - 7:30pm).