How do I know if my dog is able to have puppies?

I have a dog. She is about 9 months old. She is part dachshund and terrier. How do I know if she is able to have puppies normally? And how long will she be pregnant before we should start watching for her to have them?
Let me start with first question . While it is not a hard rule, most females come into their first heat cycle around six months of age, although I have had girls wait as long as one to one and a half years old. While many females will hold to a fairly steady schedule of coming into season about every six months, it really can vary. Some girls will only come in once year, while others may even come in every four months, but often these