I'm going to preface this by saying that while I haven't had a baby yet, I've seen my sister and my best friend go through PPD. I know it's not the same thing as experiencing it for myself, and I hope I'm not overstepping any lines here. I was diagnosed with depression a few years ago, and am already worried about how I'll deal with it after I have my baby.
You're not a failure to your child. You carried her for your entire pregnancy, and it doesn't matter to her if she came out vaginally or through a C-section. All that matters is that you were there, and that you were one of the first voices she heard. Also, don't beat yourself up over not being able to breast feed. A lot of women can't, for various reasons. My oldest nephew was born with a severe milk allergy, and my best friend couldn't produce enough milk on her own. These things happen, but they don't make you any less of a mother or any less of a woman.
As for the Acid Reflux, have you spoken with your daughter's doctor about it? There are probably medications that can help with it.
As far as I see it, becoming a mother for the first time is like starting any other new job - you can't know everything straight out of the gate. You've never been a mother before, and your daughter's never been a baby before. You're both learning what works and what doesn't. Try not to be too hard on yourself, and don't be afraid to ask family or friends for help.