So sorry OP, it's really shit
I'm militant about being incredibly open about our situation, but I understand others may not feel this is right for them
I'm fortunate enough that I've never been asked why I don't have kids, although I have often had deeply unhelpful responses when I've replied to the (perfectly reasonable) question of whether I have kids? (I think it's a perfectly innocent question to ask IF someone has kids, but not to ask WHY they don't have kids / 'only' have one child)
I reply 'unfortunately we can't have children' and whilst most people are lovely and say 'I'm so sorry' and leave it at that, there are those who like to chip in with the usual roster of unhelpful infertility bingo comments
'You never know!'
'My husband's sister's hairdresser's colleague's neighbour's cousin's PA's friend knew a couple who'd been trying for 17 years and had 14 IVF cycles and 12 miscarriages and she had blocked tubes and he had one bollock and a low sperm count, and they stopped trying and went on the adoption list and went on holiday and relaxed and got drunk and now they have quadruplets'
'Have you tried....'
'You're so lucky, I'd love to be able to have lie ins and holidays and buy nice clothes '
'Honestly they're not all they're cracked up to be'
'You can have mine if you want?!'
'Have you thought about adoption?'
'Why don't you just adopt?'
'Surrogacy is all the rage, all the Hollywood celebs are doing it, look at Kim Kardashian'
Etc etc
People mean well but really, it's deeply unhelpful and often very hurtful and dismissive of a very real and very deep trauma.
If someone tells you they are involuntarily childless (ie not child free by choice), it's OK to not know what to say. It's absolutely fine to say 'I'm so sorry, I don't know what to say'
Even better just to say 'I'm so sorry, it must be really hard'
Even better to say 'I'm so sorry, how can I best support you?'
Big hugs OP
We're at the end of our IVF journey and I can heartily recommend Jody Day's book 'Living the life unexpected', about coming to terms with involuntary childlessness
Hope you can find your way forward with as minimal input from fuckwits as possible