Please have your dog spayed after about a month from the end of her heat....unless you want her to die of mammary cancer like your previous dog.
For every heat she goes through the more chance she has of getting mammary cancer later in life.
She does not need to have a litter
, not sure why this old "wives tale" is still going around??
If you want her to stay healthy and be a good companion have her spayed.
Gina