If the mice are pregnant they usually blow up at the end. They'll really start to show in the third week and they're tummy will get really round. It'll really look like they swallowed some golf balls.
Make sure the other mice are females. If they are you can keep them together. Give her some nesting materials (like TP and paper towels) and give her a hidey house. If she starts making a nest like crazy then she probably is pregnant.
As for the rat, if she bites you think about why she did it. It sounds to me like it's just her nipping. Babies are really nippy and they do it a lot. Especially if you hand feed her treats. Every time she smells your hand or sees you she'll associate you with a treat. That's not a bad thing. When she nips you you can try saying NO in a louder voice. She'll get the hint that she's hurting you.
Make sure you don't feed her through the
cage bars. She might definitely bite you then and draw blood. So try not to give her treats through the cage bars.
If she does draw blood, then think about why she did it. Rats usually aren't biters. There are some exceptions but about 90% of rats don't just bite for no reason. If you scare her or hurt her she can bite. I don't mean hurting on purpose. One time I accidently shut my rats tail in the cage door and he turned around and bit me. I was honestly more scared for him then for me because I hurt him. I went to work feeling bad, and I felt bad all day until I came home. I gave him tons of kisses and treats...lol..
Just give her some time, and don't worry if she's nipping a little harder then usual. She'll figure out the whole nipping thing. Females are very active so she probably just wants to play.
We do have two girls that bite---draw blood etc. They lunge and go for you. They are also always looking for toes to get. aargh. It doesn't really sound like your rat is doing that. Like Vanila Rat said---rats like to clean up our boo boos. Oh and bandaids man they love ripping those off. My boys will pick off hang nails and the rough patches of skin on me too. sometimes it isn't too comfy. My rats have never nipped and run off. However it is entirely possible she was playing with you. My rat boys kind of play that way with each other. They will pull each other's hair. Poor Moe often has scabs on him because, being a double rex, he often has no hair. Good thing we have antibiotic oinments. Poor little dude.
