I'm not sure about the breeding situation (that is so sad!) but her 'sadness' may just be a transitional thing. You've only had her for a few days, correct? I brought my Levi home when he was almost 2 years old, and it took awhile for him to feel completely settled in and comfortable...even though I had met him several times previously and had even kept him overnight before bringing him home permanently. He seemed playful and happy enough, but we did have some transitional issues the first few weeks, mainly refusal to eat and potty issues.
To entice him to eat when I first got him, I would mix in wet food with his kibble. He's never refused wet food, but would often completely ignore his kibble, no matter how hard I tried to get him to eat. This worked pretty well for us. He'd usually eat the wet food, then decide to eat the kibble. Even if he only ate the wet food, I felt better because I knew he was at least eating something.
He also came to me with potty issues, and it took us awhile to get into a routine. His first family hadn't trained him well, he was doing pretty well with pottying outside with his foster family, but had a lot of accidents the first couple of weeks I had him. Once we got into a regular routine, the accidents almost completely stopped. It is a little different because I was outdoor training him, but just be consistent with the pad training and I'm sure she will pick it up.
Don't give up! It may just take her some time to settle in and feel comfortable and at home. I'm glad you could give this little girl a new home.
