Oh Emma, I can't belive how similar our situation and feelings are. I'm going through the same and finding it so hard. With DS I had to stop at 7 months because I was pregnant with DD. It was really hard to stop but nothing in comparison to what it's like this time. He wanted to stop himself because I didn't have enough milk for him and was happy to take the bottle.
This time I thought DD will never even have a bottle and I can go on for a year or longer, but after months of EDs I have to stop at 5 months. She loves to feed and I love feeding her but my milk makes her sick no matter how strict my ED is. It's a terrible feeling but she is better on HAF. If I do skin to skin to ease the transition, she sucks my neck and whatever skin she can get. I can't stop crying about it.
And I, like you, think back how wonderful it was in the hospital, before her allergies started, and she fed away and slept happily in between and was a settled, happy girl.