Breastfeeding/supplementing

Lisa
Okay so I just had my daughter via c section on the 7th and I've been ebf since. We had her pediatrician appointment yesterday and they want me to supplement since her weight is down.. I can't help but feel so emotional over this because I didn't want to use formula this time around.(I have a 19mth old son) so they gave me similac and she hates it! She spits it right back up. So I have gentle ease and gerber gentle here to supplement with,instead. My milk is starting to come in and I don't let her go passed the three hour mark when it comes to feeding. I would just like to ebf,no supplementing. Does any one have any success stories with supplementing?? Or any words of wisdom/advice?