ok. if you can feel her nipples that means they have started elongating (this happens from 90th day onwards), if they are quite long, she's about two weeks or less away from birth, from my experience.
has she started staying at the bottom of the cage more than usual? monitor her water intake, they drink a lot more a few days before birth.
the reason i was asking about the male is because they go into heat straight after giving birth so she could get pregnant again. this is not good for her or the babies as nursing and being pregnant is quite exhausting. it would be a good idea to remove the boy once you notice she starts staying at the bottom of the cage as they naturally do this a few days before birth.
you will need to make sure the cage is baby escape proof, this means that ideally the spacing between bars should be half an inch (1.2 cm) - babies are tiny and LOVE to escape.
it's a good idea to put her into a single level cage or remove shelves although my girl got really stressed when i tried to put her into single level cage so i just left her in the normal one.
you will need a scales that weighs in grams and weigh the babies every day. it's normal for them to lose a couple of grams the first day while mummy's milk is coming in but after that they should be putting on weight steadily. if for any reason your girl can't nurse - hopefully this won't happen
but she may need a bit of help if she has too many babies or if there's a problem - some people use formula, i used fresh sheep milk and goat's milk is good too.
i would let your vet know just so they are aware you have a pregnant chinchilla, sometimes there are problems and it's better for them to be ready. how old is brandy?