
Can I ask if there's any reason why she needs to have another litter, if that's why you are waiting? I had just one who came in bang on 6 months and then started cycling every 5 months. All my other girls didn't start until they were around 8 months, and cycled at that interval. And more often than not, if one was in season, it tended to bring the others in. I had that bitch spayed without issue and kept her to the end of her days as a much loved pet, as they all were. I didn't think she was that good to be honest although as a pup, she did some good winning.
To be honest, especially if she's now had a false pregnancy which may keep happening after every season, I'd get her spayed now and be done with it.