I really recommend against breeding a rabbit you got from a pet store regardless - you don't know her genetic background, family tree/lineage or anything like that and pet stores aren't exactly reliable sources of breeding stock. Also, if breeding a large rabbit to a small one, you want the male to be the smaller of the two... otherwise, there's a much higher risk of a kit getting stuck (which can be fatal to both mom and the litter).
If you want to breed, I recommend doing a lot of research, asking a lot of questions in our "Rabbitry and Show Room" section and then, once you're ready, getting your breeding stock from reputable breeders.
Your rabbit will need to be spayed in order to have a companion of either gender - it's not safe for two unaltered rabbits to live together; BOTH need to be spayed/neutered (when breeding, the female is taken to the male's enclosure, mating happens under direct supervision and then the female is returned to her own enclosure - they're never companions and never allowed to live together).