Please spay your bitch now. While it may not help, it could and it absolutely can prevent an oops litter with her son. I agree totally, wait until he is older to neuter.
Her age.. just now maturing. It isn't uncommon for them to become dog aggressive as they mature, and no, you can't stop it. The only safe method is control, keep safe, and accept that some things are simply the nature of the dog. More dogs have been killed/injured by people trying to make them get along with other dogs than anything. Dog management is the key. Absolutely thyroid testing, but don't expect that, even if she has issues, to cure the problem. Can you talk to the breeder to see how her bloodline and litter mates are?
