Exhausted

I just want to cry cause of how hard breastfeeding is.. My baby is cluster feeding and I'm not producing much of any milk.. I can tell bc I use a nipple sheild also don't hear her gulping.. We were doing great with EBF but now this cluster feeding has drained my supply.. I'm about to just cave and give her formula bc she just cries when milk isn't coming out anymore.. I'm exhausted, irritable and feel baby is also.. She won't sleep for longer than 30 min-1hr.. Jeeze nobody said breastfeeding would be this hard !!!