I agree with so much of this, especially
You never stop worrying about them and if they are unhappy then often you will be unhappy as well and if you have multiple children that's a lot of chances to be unhappy even if things are mostly ok with them someone will not get a much hoped for job or will go through a break up potentially worse.
and
I think as well these days its like your children are dependent on you so much longer than they were in the past even in their 30's they need or may need financial and emotional support.
DH and I and all our siblings on both sides transitioned to adulthood without even thinking about it - university, first job, first flat etc. None of us ever lived at home again after graduating or needed any kind of support from our respective families. Our parents were able to enjoy the next stage of their lives and their refound independence, and we've given them very little to worry about ever since.
Naively I assumed that it would be the same for us. I couldn't be more wrong. One of our DC has very serious MH issues and I can already see I will be desperately worrying about them until the day I die. Even for my other DC, who don't have the same struggles, life feels like it is going to be so much harder for them than it was for us.
When you have a child you give a hostage to fortune and your happiness will be forever intertwined with theirs. I didn't understand what that meant before I had them. So right now, no, I wouldn't do it again.