good job
i don't think people should make others feel terribly guilty about not spay/neutering pets. there are those out there that want to, but really honestly can't afford to. to me this doesn't make them bad owners, i think there are lots that love their pets and take in a stray or something and feed it well but just can't quite get that big bill saved up for. thank heavens for spay/neuter clinics and vets that do low cost services on rescue dogs and cats! they are truely saints.
spay/neuter if at all possible for your own sake and the pets. overpopulation is what put that rescue pup on the streets to start with and you don't want to be another addition to the problem and if you can't afford the bills, look to a low cost clinic or a shelter to help out. some shelters will foster a dog/cat that you found and are willing to keep and help cover it's vet costs and allow you to adopt after you've fostered them awhile during their care period...
good luck and thanks to those that do spay/neuter their pets!!