Hi there and thanks for your question!
It is going to be hard to answer your question. Dogs generally are pregnant for 63 days. So, if you know when she was bred then this question would be easy to answer.
Dogs can start to produce milk at different stages in their pregnancy. Usually you will start to see weight gain at about 35 days. An ultrasound can detect a pregnancy after around 28 days (sometimes before). An xray will detect a pregnancy after around 50 days.
Here is some good information to help you:
Hope this helps!