Please get her spayed now. Call the vet tomorrow. She could come into season anytime in the next 6 months, but most likely soon. From your question, I can't imagine you have done the work needed to become a responsible breeder. Take a look at Should I Breed My Dog?
Can you begin to follow those guidelines?
A small dog like that isn't going to have that much discharge, but must be protected from being bred. Responsible breeders never breed a dog before 2 years. She could become pregnant once she comes in season. It is very stressful for a dog to be bred when it is less than a year old. Please make sure it doesn't happen.