It's okay...when I left Taz I made them promise me that they would take extra good care of her and then I got teary eyed even though they promised. Your girl will be okay and you can lavish a little extra attention on her when she gets home. (((( Hugs!)))))) I will think good thoughts for you!
Odie was sick (tummy issues) after her spay, so she didn't eat a full meal like she normally does until a week after. The vet told me that even without diarrhea, it's normal for it to take a couple days for them to get their appetite back. Make sure she's staying well hydrated.
I'm late on this but, hope she is feeling better today! If you have any concerns I wouldn't hesitate to phone the vets office to ask any post op questions. Alls probably fine, but sometimes we as pup parents need some reassurance!
IMO though, sounds normal