It doesn't sound naive, I don't think anyone expects to start parenthood in the aftermath of trauma, or can really have a proper understanding of what that can feel like until they've been there. The hormones alone are, frankly, a shitshow, and then you add in on top of that no sleep, caring for a newborn, trying to work out feeding, so much 'advice' to wade through, constant comparisons with other people - it's all hard enough without also having to deal with the aftermath of a traumatic experience.
I remember being right in the depths of it after my first and it's just awful. When I read your post I just wanted to give you the biggest hug cause argh, it's just such a horrible set of feelings. But (and I know this sounds cheesy, so apologies) for all the things I'd change about my birth and postnatal experiences and first few years of parenting if I could, there are also things I wouldn't, including how hard I know I worked to be the best mum I could in far from ideal circumstances.
With feeding, I'm really sorry it hasn't worked out the way you wanted. It sounds like you did everything you could to make it work. Sometimes it just doesn't, and that's no reflection on you, just as a tough birth is no reflection on you either. It's neither good nor bad, it's just what happened.
Take a bit of time out if you can let your husband have the baby for a while (I struggled with that too, but in hindsight I did need some rest time), and push all the professionals around you for help.
Above all, be kind to yourself. You are doing wonderfully, and your daughter is tremendously lucky to have you xx