i think i have a girl rat .. with a boy rat

Question
ok, so about a month ago i got my first rat, hes a all white albino rat, and hes is the nicest pet ever! Well about 2 weeks ago i went and got him a new rat, because they are suppost to have company. Well this lady needed a home for her rat, and she gave me "him" for free. Well being a first time owner i thought that it was a boy, its so little i didnt think that the testicles had you know dropped or watever yet. Well i was sitting neer the cage tonight, and i noticed that Ambrose, my boy rat, was humping the new little rat. the new rat is about 7 weeks or so old? I thought that maybe they just do that, but now im scared that the new rat is a boy. also i checked it, and there are no testicles, and there is a hard white substance near is rear..is this a girl rat, and is it going to have babies now ? please help..

Answer
Look for nipples on your suspected girl rat.. do you see any? If so, yes, it's a girl, and most likely yes, she's pregnant -- especially if you saw your boy breeding her.

Separate them immediately and plan on having your boy altered OR get him a new cagemate who is DEFINITELY male.