For us, our number 4 was a happy surprise and tbh having 4 is actually easier than when we had the 3.
Now that my baby is getting bigger, I'm hoping for number 5.
DD is 10, DS 7, DS 5 and DS 2.
I have 2 at school ( catholic) and the 4th ( and any others) are free ( except for the building levy) as long as they are all at a catholic school in our diocese.
My theory is I will never ever regret having a child but I may regret not having one.
Jmo I say go for it :-)