Oh, goodness, I am so sorry to hear your vet won't spay or neuter, that does not bode well for your bunnies' long-term health! Maybe look some more, is there any vet school in your state that might do it? That's a lot of bunnies, you're gonna need more cages!

Female rabbits who are left unspayed tend to die earlier from uterine cancer or uterine infection, sadly.