
Guest do you work your bitch? Reason I ask is that there are lost of so called and Actual Jack russells out there. they are not a Kennel Club Recognised breed, and serious russell breeders will be involved with working their dogs and keeping a recognisavble type.
If you only want to have another pet it would be a far better idea to get naother pup from an expereinced breeder or from the many of this type that are foudn in the rescue centres.
Breeding carries a lot of responsiblilities to the pups for th3e rest of their lives and to their families. In a breed that isn't registered it is even more difficult to do all the required research into the ancestry of both dog and bitch to be sure to produce healthy typical pups of good temperament. You could have Grandparents of that nice dog with Slipping Patellas, nasty temper, or type you don't like, all of these could be passed on to your pups. Also how are your bitches parents, are they healthy and of good temperament?
You say your bitch is young, she ought to be at least 18 months and better over two years of age before having a litter. Have you bred puppies before. Would you recognise and know what to do if there were problems. Sadly bitches die whilst whelping sometimes, or whole litters die after birth, or you have to have unvialbe pups put to sleep. Not eveyone has the stomach for what goes with breeding.