Do you have complete pedigrees for the rabbits you intend to breed? If you don't know their ancestry you're risking genetic problems with the babies.
What breed(s) are the rabbits? I know some breeds are incompatible because their skull shapes are so different, their offspring suffer from serious dental problems. Breeding two dwarf rabbits means that about 25% of the babies will be "peanuts", which never survive.
What do you plan to do with the babies once they are weaned? Can you keep them all? Will you be able to absolutely guarantee they'll go to good homes with knowledgable owners?
What happens if the female suffered complications and dies, leaving you with orphaned kits? Do you know how to hand-rear?
You need to think about temperament too. "Grumpy" doesn't sound like a good trait to pass on to the offspring.
Is the enjoyment of breeding worth the risk of genetic problems, death of the female, death of the kits, uterine cancer because the female isn't spayed, or your babies spending the rest of their lives alone in tiny hutches being ignored by owners who got them for kids who quickly got bored with the cleaning?
I bred a lot of guinea pigs when I used to keep them years ago. I would never do it now.