Although I am no longer a parent to an only child I have been for the last 9 years. Dh and I tried for for 8 years to have a second child. Our new baby boy is almost 7 weeks.
Our DD always asked for a sibling. She wanted someone to share her life with. Yes life was simpler with only dd but I do not regret persevering to have another child. We were told that IVF was our only option, but after losing 40kg, I have clomid a second go and now have a gorgeous little boy because of it.
How many children you have is a very personal choice. No one can tell you if one is right it wrong.
For me, I always felt like I wasn't done.
Now though, I feel completely finished.