You have to understand that you (most likely) no nothing of your guinea pigs genetics, or breeding for that matter. You are putting your current guinea pigs in danger by breeding them. What if your guinea pig has 4 or more babies, how are you going to care for them? There is such a thing as a lethal gene, when you breed two roans your outcome is a white guinea pig with deformities. You would also be risking your female's life. Do you have enough money to send the female and baby pigs to the vet if needed?
You need to take all of these things into consideration before you breed. Instead, a much better idea would be to go to an exotic vet and get them to neuter your male.