My son is now 4 days old and has lost 11% of his birth weight. He is also slightly jaundiced, but not bad enough to need lights or anything. He is great at nursing.. My body just hasn't caught on. My milk isn't in yet and I'm trying not to stress since it's only day 4.  This is EXACTLY how it went with my 3 year old... But my supply worsened because we supplemented with formula and it was all gone by 4 months... I DO NOT want that to happen again.