Well, well, well. It's people like you that contribute to the overpopulation of cavies. I'm not sure how it is in Australia, but I know in the U.S., approximately 100,000 sweet, healthy cavies are PTS because they couldn't find a home.
Cavy pregnancy is dangerous for both mom and pups. I see you are just 13. Caring for many cavies costs a lot - I am not able to keep 46 cavies (I have six and at limit). Are you parents kicking in for expenses? What about a vet? Contrary to popular breeder belief, a vet is vital in the whole process. Birthing mothers can have a lot of trouble passing the relatively large pups. Only a vet can save the sow and the pups should complications arise. Will you be able to take your sow to the vet ASAP? I reckon one cannot drive a car legally at age 13.
Have you studied genetics? Are you aware that a certain
birth defect is easy to produce with a certain mating? Do you know the genetics of the lines you will cross? All this MUST be thoroughly checked and researched.
Breeding guinea pigs, though it seems like an innocent pastime, is actually an activity best suited for adults, and not all adults at that. It is
not for kids. Plus you will be contributing to the problem of guinea pig overpopulation.
This forum is run by a rescuer. By that very fact, this forum is pro-rescue, and anti-breeding. Many of the members share the site owner's passion for protecting these sweet creatures. Some members even rescue themselves and put a lot of time, effort, moeny and emootion into cleaning upmesses theat breeders leave behind.
I urge you to make the responsible decision NOT to breed.
P.S. - I'm old and have trouble with chatspeak, poor punctuation and spelling. Please don't use it in the future. Thank you.