Sleep help

My daughter just turned 14 months the 19th. For the last 4 months she’s been up on average 3-4 hours awake at night between 2-4 wakings. Brought it up to pediatrician, I’ve been giving pediasure at night per my pediatrician recommendations. She eats 3 meals a day and 2-3 snacks a day. She is diagnosed autistic, but is there any way I can help us both get sleep?! I’ve changed sheets, blankets, diapers, water, changed pajamas in the pitch black room, have her soft music going but there’s nothing that’s helping! Last month the pediatrician said to give 1mg melatonin, I’ve done that, nothing. I’m at a loss. Her behavioral therapist is at a loss too. I’m going on 4 months of 4 hours of sleep (on a good night) I need help. What can I do. I’m crying because she won’t sleep. I can’t function on 4 hours of sleep, I have 3 high energy dogs as well. I’m running on fumes hopes, caffeine and nicotine.