Well it's up to you if you want to breed her, but there are so many unwanted cats in rescues that breeding any cats is something that i would discourage most people from doing, regardless of whether the cat is pedigree or not. Not everyone will agree with me, but I'm not opposed to breeding pedigree cats because reputable breeders do that for reasons other than they just want a litter, kittens are cute, their friends would like a kitten etc. They do it because if they didn't some beautiful breeds would die out or be left in the hands of backyard breeders, and because they want to preserve and improve the breed. They learn everything they can about the breed and the breed standard, they learn about genetics and hereditary diseases. Then when they've acquired that knowledge, they consider breeding. They do it for the love of the breed. If those reasons are absent, then it just becomes a case of producing yet more kittens into a world where there are already so many without homes. I'm afraid I can't support that, however beautiful the cat is. If you said you were passionate about ragdolls and wanted to become a reputable breeder who contributed something to the breed, then I'd be happy for you. But why do you want just one litter? Do you think the health risks of not having her spayed are worth it for just one litter?
I know ragdolls are slow developers (not sure at what age they first come into heat) but bear in mind that every heat that comes and goes without her being mated poses a risk to her. You may not be able to wait as long to mate her as you'd like.
Sorry if I've offended you. These are just the questions that any good breeder should have asked you if you had asked for a breeding cat. I'm not impressed with the breeder you bought this cat from.
Having said that, I do wish you luck and hope that everything goes well for you and your new kitty, whatever you decide to do.