Is my baby rat pregnant or just fat?

i got her over a week ago. she had a liitle squishy baby belly when i first got her, but know it seems more rounded and plump. i didnt think i was feeding her too much, she eats peas (fishing for peas), and her regular kibble food, and some small ammounts of milk. what are some signs that she could be? and if she is, how long till she has them? i think she might be epileptic so if she is pregnant, could having seizures hurt the kittens? 8-] thanks