My kitten is sleeping all day with white gums. Could it be parvo?

Oh dear, poor Luna! It sounds as though she is extremely ill. In cats, parvovirus causes panleukopenia (aka feline distemper virus), which can be a life-threatening issue. Typically, vomiting, diarrhea, a loss of appetite, fever, and lethargy with extremely low white blood cells are found with panleukopenia. While it is still possible that Luna is affected by this virus, other possibilities such as blood loss anemia from fleas, exposure to anticoagulant rat poisons, blood clotting disorders, or bone marrow issues are also possible causes of her white gums. All of that said, white gums are a medical emergency because this indicates either a severe anemia (low red blood cell count) or extremely low blood pressure preventing blood from moving to the periphery of the body. At this point, I strongly recommend taking Luna to an emergency vet immediately for evaluation. I hope that all goes well!