Plenty of info there for you
. As regards whether or not she is pregnant, I believe it is very difficult to tell but sometimes just before they are due to give birth they get very large at the back end. If that helps. See how it goes for now. Best to let her settle again for now. She maybe felt the house was a bit cramped and so moved in somewhere else and goes back to feed the pups. She might have felt they were a bit exposed in the house as well hence trying to move them under the green tray. Just see how it goes but best not to get too close to the cage to keep looking - and keep a distance. Just keep putting plenty of food and water out.