Is it selfish to want a kid in your 40’s?

Hi all- here’s my back story:

I had a boy when I was 28. The dad is not in the picture and I did the whole thing on my own.

I met a guy - 2 years later- we moved in, and are now married. We both have custody of our now 12 year olds and he has a 15 year old from a previous marriage. He’s getting a visectomy reversal in 2 months so we can have 1 together. I feel like I’m more on board than he is sometimes with wanting another kid. He wants to travel and has given his life to his kids , he’s 2 years older than me, plus he was married a few times before me and now kinda just wants to live - then die later.

I’m fully happy that I’m married because I’ve never been married and never wanted to be. I’m thinking THIS IS GREAT! And we can have a family.

I told him I’m conflicted because I don’t want to go thru having a kid all by myself again- so if we go thru with having kid #4, I want him to want it with me too.

My cousin who told the same age is traveling and loving growing old with her husband. I don’t want a future without another kid. How ridiculous is this situation?

I’m half thinking- whatever- if it happens then great. But I also feel it to my core that if we did not have a kid I would never ever be ok with that. I like being a mom. I like helping and nurturing. It’s who I am.

The last thing I want is for Themis difference to be a thing between my husband for us and the rest of our lives to have him regret having a kid with me. It’s kind of a slow torture situation to be in.

Thoughts??