I think it sounds kind of weird when you say
I was the last of my brothers and sisters pusehd through the birth canal,
and also if you want all these events
I wanted to write a story about the lifetime of a dog who has gone through shelters, emergency health situations, and finally finding the perfect family
in one story you might not want to start it from when the pup was born, it would be a looong story to explain all of that. Just my 2 cents