There are lots of threads on here and info on the internet that puts forward the pros and cons of spaying, so at the end of the day you have to go with your heart or head.
From my point of view I would spay but only after she has had her 1st season. My vet had said at 6 months, but I explained that I wanted her to have a season first to enable her to mature, so mine have been spayed between 14-16 months( obviously depends on 1st season but most seem to have been 10-12mths)
My first 2 girls I didn't have spayed, one died aged 9 from mammary tumours which she had removed 12 months before, but unfortunately had spread to her liver despite being caught early. The other died at 8, 4 months after having to have an emergency spay for pyometra. My first girl also had phantom pregnancies with most of her seasons.
After that,and realising that I could have at least prevented these conditions I have had all my other girls spayed. Boys are different, but I still would probably have them neutered at about 2 years of age.