There are many children that have one on one aides that are not as bad off as your daughter. I would be livid if my child came home in the same diaper she went to school in. How would the teacher like to sit in a dirty diaper all day? Any to have hardly ate or drank during the day? This could lead to medical consequences.
My son doesn't have an IEP, so I can't help you there, but I think you could get an aide for your daughter if you keep pushing. If you don't get anywhere with the IEP meeting, there are other steps you can take. Her needs are NOT being met. Not even her basic human needs are being met at school, let alone her academic ones.