The only child is now 21y.
She is confident, secure, caring, happy and engaging.
She went through the odd phase of wanting a sibling, but then so do children who have siblings ime as well as not wanting siblings. But it was only ever fleeting.
Growing up she always had lots of friends and we enabled these through play dates, etc and being willing to host them and sleepovers, driving her places as many friends weren’t walkable local ones and encouraging her to join groups if she wanted to. She was also happy in her own company and was self sufficient in keeping herself occupied at times.
She is now 21 and finishing university. She has lots of friends and is an independent social young woman. She’s just finished work placements where she was well liked and respected, finishing with a glowing report. She’s about the jet off for a summer adventure meeting, living with and working with new people she is yet to meet.
We (as does she) feel that not having a sibling hasn’t held her back at all and she enjoyed her childhood without being lonely.
We are wise enough to know that even if she’d had a sibling there was no guarantee they’d have played together or been great friends, and there was no guarantee they’d have been supportive siblings as adults. Bith dh and I are lucky enough to have supportive siblings but know of plenty of situations where this isn’t the case too.
There is never a right or wrong answer with siblings. Some only children love it, some don’t. Some children with siblings love it, some don’t. You can never judge which experience you will get.
So just enjoy what you have.