White Cloud, Pregnant?

[bachina]

We have two white cloud mountain minnows (i know a few more is advised, but we don't have a few more just yet). One is the orange one, the other is silver. About a week after getting these fish, the silver one looked real fat. real real fat. However, it looks quite healthy, nothing is impaired... could it be a she? and is she pregnant?

How long do these fish stay pregnant before they lay their eggs? Is it possible for them to just never lay their eggs if the conditions are not right and for them to just carry these eggs forever? How do you tell if they're pregnant or fat?

thanks so much for the help!