Ophelia, I haven't read your whole thread, just your OP, but had to reply. IO have HUGE symnpathy with you. DS2 had chronic reflux which resulted in severe FTT. As a result I had PND. It is impossible to understand, if you haven't been through it what an ordeal it is.
It is without doubt the toughest time I ever had, but it does pass. If you could see my FTT baby now. He was undersized for the first four years of his life - really tiny. I remember a friend who had her baby same time as I had DS2 then had a second baby and her newborn was bigger than DS2 at 20 months. I cried!
Now he's enormous! Tall for his age and in clothes one or two years above his age (having spent the first five years of his life in clothes a year or two smaller than his age. He is also now in the top set in his class, after being bottom of the class throughout infants (I'm sure linked to the reflux as he was so weak and tired) and best of all - he really loves his food.
But he didn't for years, I'll be honest. It was a slow process. Like your DD, he had bottle milk for ages after most DC are weaned, and lived on it in preferwence over solids. Nothing I could do. If I didn't give it to him, he didn't have anything.
So here's the advice I collected that helped and comforted me most:
It WILL pass.
Never take advice from or expect someone to understand unless they've been through it/are genuine specialists on the subject. Even health professionals. Only take advice from people who believe you when you say she just won't eat.
Try to eat with enjoyment near her.
Let her eat rubbish if she enjoys it (once she's at weaning stage.) What's important here is teaching that food can be a pleasure, not something to be frightened of. DS2 learned this from icecream!
and the best advice from my SIL was, if she throws up, offer another bottle straight away. Seems counter intuitive and it doesn't always work, but if she really is starving herself almost to death, as DS2 did, it's important to just get a few more calories in whenever you can.
And a trick I discovered by accident was to post food into his mouth when he wasn't aware he was eating. I cut up minute bits of anything he'd just about tolerate and tuck it in his mouth while he was playing. Bit by bit, it went in.
Then at meal times, I'd get out ice cream, so he learned that sitting up to table was enjoyable.
Sounds bonkers but normal advice just didn't work.
i really REALLY hope it passes soon for you both. Hang on in there. you feel like the worst mum in the world at the time, when in fact, however deep and dark the feelings go, you're actually doing your best in a really cruel situation and you're saving her life.
Sorry it's such an essay.