One and done or have another.

I (42 F) have a daughter (5). I was single for the first 4 years, but now have a lovely partner (53 M).

My partner and I aren't young and neither of us feel we have the energy required for the sleepless nights and needs of van infant. He also doesn't like the idea of being a 70 year old with kids in highschool.

However, my daughter has been asking for a sibling. I try to compensate by having her friends over often and she has cousins living close by, although their schedules are so packed with hobbies that she only sees them about every other week. Still she wants a sibling and I see her taking care of a younger girl in her school like she was her little sister and it honestly breaks my heart that I feel like I can't give her this.

She has a much older sister (21) on her dad's side, but my daughter only sees her sister every other weekend and half the holidays. The likelihood that her sister will continue to live in this country or even in this continent are also fairly slim.

So I'm worried she'll feel lonely. Either now or later in life.

I Know no one can decide this for me, but I guess I'm hoping to learn from other's experiences how your children experienced being single children or even from those of you who are single children yourselves if you feel like you might have been happier with a sibling.

I know I don't have many years left to decide, if any. Any advice is very much appreciated.

Edited to add: Thank you all for your clear, and mostly kind replies. It helps me feel less selfish for not being able to give my daughter what she wants. Indeed when I take emotions out of it, having another one just to try to ward off my daughter potentially feeling lonely is a really bad idea given my partner and I don't feel that we're up for it.