As she has a possibly dodgy background, my first call would be the vet. Many think a spay before a first season is beneficial, anyway (reckoned to reduce the chances of mammary tumours). I'm not sure how early a boy is sexualy mature (ie producing active sperm), but there is always the exception, who matures earlier than normal.
On one of the many vet programmes, over here, was a 'sick' Blenheim, only very young, who gave birth, at the vets, to three puppies (luckily healthy, but tiny ) , when she had been bought from someone who only had puppies together , so Dad was a baby , too.