Mommy question

My son is almost 6 months old and he still wakes up multiple times at night to eat. I feed him as much as I can throughout the day and right before bed but he always wakes up to eat. Recently I've only been producing enough breast milk to feed him 2-3 times a day, then I still give him formula because that barely fills him up. I've tried everything to get him to not wake up durring the night and nothing works I know I'm going to have to just get him used to just going back to sleep without eating but he SCREAMS if I don't nurse him or give him even just one ounce of formula then he falls right back to sleep. I haven't had a full night sleep since before he was born he woke up at night even before he was born... and I'm about to fall apart. Can someone tell me how to fix this please??!!