Pregnany Signs

ok I have a female that I'm afraid might be pregnant. I got her and her sister 13 days ago, I adopted them from petco, and I have no idea if she was exposed to a male before arriving at petco. Shes about 10 weeks old atm, was 8 weeks when I got her. Here are her symptoms and I'm just wondering if she might be pregnant.

-her stomach seems larger then usual
-her stomach seems firmer then usual
-her stomach feels ever so slightly lumpy
-shes more skittish then usual
-she sleeps and hides for then usual
-shes not nesting that I can see but theres nothing but bedding in there, so she might be nesting and I just can't tell.

Any ideas and advice would be awsome!