Our dog is Pregnant now what!?

I wanted a small dog for our children ages 12 and 8. I found a military woman who was trying to find a home for her Corgi - we loved her and she had all her papers, shots - you name it. I have had her for 42 days now, Vet said just by feeling her and listening to her, she is pregnant. Go figure.. I can not get a return call from these people.. I am sad and angry at them! I wanted to have her fixed because we did not want to bring more dogs into this over crowded world. Now we have people lined up who would love one.. and of course we are choosing carefully. I have no clue what breed the other dog was, praying it was her size and not bigger. I am doing my research now about birth of pups.. any advice? We did not get an xray - worried about radiation and we are thinking about an ultrasound but figure heart beat sound and vet feeling, was good enough. She is def prego.. can I get her fixed right after she has her pups? She is an inside dog.. and also, she is only 9 months old.. : (