Miha, you sound like a brilliant, loving, attentive mother. "She is now the happiest baby ever"... you did that.
I was desperate for breast feeding to work and it just didn't, my supply just never picked up. I got all the advice from midwives, bf consultant, friends who had bf, you name it... "Keep at it and the milk will arrive, don't use formula as it will interfere..." I listened, refused to use formula, pumped and nursed around the clock... and my baby had to be admitted with dehydration at a week old
. I can't even look at the newborn pictures with the little chapped lips and jaundiced skin. I wonder how I didn't see how desperate things were getting. I feel sick when I think of what might have happened of it had gone on another day, another weekend....
It's so hard though, when you're a new mother you don't really know what's normal, you don't know if they're not getting much or if it just feel that way.
I beat myself up then for 'failing' to bf and having to use formula. I beat myself up later for being so obsessed with 'breast is best' that I let my baby go hungry and become ill rather than give a perfectly suitable and available substitute. So I understand why you're beating yourself up, but you shouldn't. You don't deserve it and neither did I.
There were no ill effects at all once my baby started gaining. Happy, healthy, thriving from the first bottle of formula on. It's a decade later and I have a very bright, very athletic, very social, very happy, very wonderful kid.