Ten weeks is way too young to start breeding a female. If you've had them in together for any amount of time, they are most likely pregnant though. I would split the male from them asap. Most females that are bred so young are horrible mothers, they don't have many pups and most do not survive.

As far as being able to tell if they are pregnant, in the last week of pregnancy, there is no missing it. I have a few females that I've sent into rotation. As soon as they become noticeably pregnant, I will take pictures.