Since your bun is moving around fine and doesn't appear to be behaving like she is in pain, the lack of appetite is likely due to nausea from the anesthesia. I've had this happen a few times and it just takes time for the anesthesia to wear off. Try offering her her usual leafy greens like green leaf lettuce(not iceberg), cilantro, parsley, carrot tops, etc, as some buns will eat these when they won't eat anything else. But if she still isn't eating or not enough, you should continue the syringe feeding. If mushy pellets aren't working out, you can usually get a syringe feeding mix called Oxbow Critical Care, from your vet. Plain canned pumpkin(not spiced) also sometimes works well. I will make the syringing mix a thick soupy consistency, and feed about 3-5cc/ml per lb of body weight, every 4 hours. You just need to be feeding enough to keep the digestive tract moving and prevent stasis from occurring. You do need to be careful handling your bun because of the recent surgery. Wrapping in a bunny burrito can work well if your bun is fighting it.
[ame]https://www.youtube.com/watch?v=8iGZVYVm5Bg[/ame]
Any vet that doesn't believe a rabbit needs pain medication following such a major surgery, isn't a very rabbit savvy vet. It's well established that rabbits need good pain control. A rabbit in pain is one that usually won't eat. Even though your bun likely isn't eating due to nausea, you still want to make sure the pain is kept under control for a few more days. So it would be good to still push for a couple more days of take home pain meds, usually metacam/meloxicam.
http://www.veterinarypartner.com/Content.plx?A=500
Like stevesmum mentioned, it's also important to make sure your rabbit is staying warm. Their temp often drops due to the anesthesia, and a hypothermic rabbit won't want to eat. You can usually tell if they are too cold by feeling their ears. If they seem really cold then your buns body temp is probably low. Use a heat pack and/or warm towels to help warm your bun up.
http://www.bio.miami.edu/hare/opcare.html