Without breeding / pregnancy they have a very HIGH risk of pyometra (uterine infection). Surgical correction of this condition is never cheap and not always successful. Lastly, dogs that are not spayed before age 2 have an 80% chance of developing mammary cancer.
You'rebasically saying, 'you're damned if do and damned if you don't'. I have a female and had her spayed at nine months old. Now she's at risk for uterine infection but not mammary cancer? If I read this correctly, the best option would have been let herhave herfirst heat cycle then spay her?