Thank you for starting this thread @ChipsRebecca
This could well be my future too. I am an only child, childless (not by choice) and my cousins are not close to me (they are close as siblings, but would never include me in that - I am just surplus to requirements).
I do have a partner though and also a very good friend who has hardly any family either, so I am not entirely alone. I would be really happy if I could have a child, but I'd be an older parent, and I am not sure bringing another innocent soul into the world (probably another only child) with zero extended family network would be a kind thing to do.
Do you ever feel a certain kind of 'shock' that you are in this position? I do. If I were ever to find myself completely alone in the future, I'd feel very much like, I didn't deserve it, if that makes sense? I think I am a kind, friendly and thoughtful person. I know life is essentially just random luck, but I can't understand why I face such possible solitude whilst others are surrounded by big family networks.
Likewise, I worry terribly about the future. Being entirely on my own as an elderly person and maybe dying alone too. 😞 I hope I can live in a retirement village type setting though where I could access support if needed, and maybe have the company of friends. I also hope that AI might make some of the practical aspects of coping with old age easier too - medication management, POA (at least the financial side).
Best wishes to you and also to anyone else facing this.