thank you and hi, I’ve had her for a year, she is in the top half of a FF with a male on the bottom. The little trap door in the center has been loose and she has been slipping through for at least 4 weeks since I had last messed with the lock between cagesHi.and welcome to the forum.
That tummy does look quite round in the third photo, but its still probably hard to telll for sure just from a photo.
As Rats4All said, how long have you had her? Could she have come from a situation where she was in with a male? Does she have any cage mates that could mistakenly be male? Any info like that would be really helpful to try and help us figure out what's going on with that tummy. Rats are only pregnant for about 21 -24 days, so that can help with dates and things.