You feel conflicted because of that one simple phrase: breast is best.
It is rammed home over and over again, in pregnancy books, by midwives, at NCT classes, by HV, on TV.
We're led to believe that formula is up there with crack cocaine and this is further inflamed by midwives and NCT classes and HV saying "we can't talk about formula only breastfeeding" and the attitude " well why do we need to talk about formula when the instructions are on the packet?!". It's all bullshit.
New mums should be told about all their feeding options. It should be made clear that it is absolutely fine to feed in whichever way best suits you and your baby because mums mental health and well being is vital to a healthy happy baby, and mums should be able to feel that they can get the advice and support they need about their chosen method of feeding even if the instructions are on the packet sometimes it's nice to be able to ask questions (evident from all the bottle / formula threads on parenting websites).
In every other aspect of a woman's life choice is always spouted as the most important thing, abortion - it's a woman's body and therefore her choice; sex - it's a woman's body and therefore her choice; make up / hair colouring / working / child care every aspect of life comes back to equal rights and choosing to do what best suits you as a woman, but somehow breast feeding doesn't apply and all of a sudden no matter how miserable it makes you, no matter how uncomfortable it makes you you should just suck it up and keep going because it is what is best.
Well sometimes it really isn't best and the sooner this is put out there and the alternatives become acceptable then maybe all this angst and guilt wont be so paramount and people can do what they actually feel is best for them.
Sorry for my very long rant 