i would say she probably is pregnant, you will know when she is ready to give birth when she goes off by herself, usually in the plants, unless you have lots of plants the young wiol be eaten by the mum and the other fish.
yes your female is pregnat as far as when she will give birth alot of times I have noticed that my females all go to the bottom of the tank usually a corner and then you will slowly see between 10 and 15 babies swiming around and resting on plant leafs. but good luck just remember they won't show their colors right away.