I'm thinking that she doesn't actually have a hemangioma. Usually those begin involuting around the age of one. Have you been seeing a specialist all this time or has it been a long time since you have been for an appt. ?
I would definitely see someone who knows something about other birthmarks/malformations to make sure the diagnosis is accurate and then maybe they will have some other ideas for treatment options since they vary for different types of birthmarks. Good luck! Keep us posted!