I'm so sorry to hear this.How did the previous vets miss that?
Please do share this knowledge every chance you get that with female snakes, it's always possible for them to attempt reproduction entirely on their own with no mates around. It's how many species tries their best to survive. It also doesn't matter if they're snakes that have live babies or lays eggs.
Egg-binding kills, & sadly, it's slow. So sorry for your loss. Too bad the ER vet wasn't the first one you saw, but then you'd probably have needed a vet with the skills to surgically spay her. I had a rat snake many years ago that developed an ectopic pregnancy & she successfully had such a surgery, but you need a real experienced herp/exotic vet for that, otherwise euthanasia would be the kindest thing.
May she rest in peace.![]()