
You've left it far too late for this season, I'm afraid. Your best bet is to contact her breeder who, if knowledgeable, will be happy to help you decide which dog would be most suitable for to match your particular bitch's qualities.
Also of course she'll have to have passed all her breed-relevent checks for hereditary conditions (a general vet-check
isn't enough). This will include hip-scoring involving an x-ray and a heart check. The hip-scoring will take several weeks to get the result, so you're looking at next season at the earliest.
Also at 5 years old she's really too old for a first litter ... it could have serious consequences for her health.