It all sounds fishy to me. How can a breeder decide for a good breeding dog when she is 6 months old? How about if you get stuck with 10 pups?
If she is lonely, (if you mean without any human company) you need to find a way to spend more time with her or get a dog sitter. And, if she is lonely now, how can you take care of a litter? That is a 24/7 job.
There is a lot more to breeding than mating two dogs.
Take freestep's advice.
Deja, GSD, sable WL, female, born 11 / 2013
Cam, Rough Collie, sable, male, born 8/2015