The previous posts are giving you great advice. I agree with YorkieRose, there's a risk a losing the mom but I don't think it's too high as long as she gets veterinary attention if something goes wrong.
I think she can be bred at that age as long as she's not too little. If you decide to go ahead after having weighing all that conciencious breeding involves, I'd advise you to have a good vet or experienced friend you can count on in case there are labour problems. Many years ago I almost lost Sally (she's already dead now) because she couldn't whelp, she was increadibly big carrying seven puppies which was far too much for her size and unfortunaley I had the misfortune to be refused help by the vet when I called him. It was a miracle she made it after all. She needed a C-section and these undesirable people at the clinic kept telling me all the poor thing had to do was dilate more and she would whelp by herself. It was almost 48
hours after the onset of labour that she was finally operated on. All her puppies died and as I said she miraculously survived.
I'm sorry if I've scared you but I just would like to stop anybody from going through what my family and Sally did during those days.