Aww, what a cutie! In my opinion, I'd say she's probably about 5 - 6 weeks old, but I'm not an expert on rat ages ^_^
Since I read your post in Say Hello as well I thought I'd throw in some other stuff too. You should really get another rat as a friend to your little girl. Rats are very social and need to be with other rats. Also, if the aquarium in the second picture is her permanent cage, you'll need to get her into a good wire cage ASAP. Ammonia builds up quickly in aquariums because of the poor ventilation, and that irritates rats' sensitive respiratory systems. Also, I can't tell what kind of bedding that is, but it looks like pine. That also can cause respiratory problems because of the oils, so you should get her onto something like aspen or Carefresh Ultra ^_^
Read through lots of posts on here and ask lots of questions, because there is *so* much great information here. Most of what I know about rats came from here
Just to respond to some of the things you said...
The aquarium Willow is in right now is just a temporary home. In a couple days she will be moved to a nice big cage with lots of toys and room. She will also soon be joined by a new friend. My roommate will get getting a rat around the same age (and of course the same gender) and they will be living together so they both have a friend! Oh yeah...and the bedding isn't pine so no worries! Thanks for the estimate on her age as well as all the good advice. I look forward to reading a lot more info on this forum!
i dont know if the whole idea of having ur room mates rat in with her...i mean it sounds good at first, but what if things turn sour or ur room mate moves out....that would mean that willow's little friend would leave her, and she'd be a sad ratty......and dont forget about QTing the room mates rat, and dont just throw them together in a cage, ya gotta introduce them first...other people on here will know more than me.....and will probly set me straight if i said something wrong...but thats my opinion
Don't worry guys. I know all about that stuff too! My roommate said she is going to leave her rat with me when we go our separate ways in 2 years...that's how much school we have left. I am definitely going to check out all the great info on here first before we get the new little one just to make sure I know everything I need to!