I agree with Cinnybun. Don’t go to bed unless she’s eaten sth. It is common for bunnies to not want to eat after a spay, but they MUST eat or their system is at risk of shutting down. If she won’t eat even the yummiest sprig of cilantro or parsley or some other favorite, you’ll have to syringe-feed her. You can make pellet slurry like Cinnabun says although a whole cup of pellets sounds like a lot to me, I’d go for a table-spoon -you can make new mix tomorrow if she still isn’t eating.
She likely feels uncomfortable. But since you don’t know the exact dosage of pain meds she’s had, you’ll have to just wait until tomorrow before you give her more. Bunnies tolerate rather a high dose of Metacam, i.e. a higher dose per kg body weight than cats or dogs, not all vets take that into account.
Keeping her warm is key, as Cinnybun also already has said. A hot water-bottle or a heating-pad or if she accepts sitting in your lap with a fleece blankie on her. Painkillers lower body temp as a side effect + buns that have been under have a tendency to become hypothermic.