I'm very sorry for your struggles. Just so you know, it almost certainly wasn't your body that failed - it was poor medical advice. Babies are SUPPOSED to lose weight in the first few days of life. Their hunger makes them suckle, the constant suckling opens the lactation floodgates. The current American practice of supplementing neonates with formula often  disrupts the feedback loop and prevents the mother from ever lactating at normal capacity - exactly what happened to you :-(