I really feel for you, dd was the same for the first 6 months, like you I posted on Mumsnet.
For us, it was lack of sleep during the day that was making dd so upset. She would literally scream for hours while one of us held her. The car/pram didn't work either.
There's no magic solution but I second the Moby wrap and a dummy. I used to jiggle about in a dark room with white noise on, repeatedly putting the dummy back into dd's mouth until she slept (trying not to think of other new mums out at baby groups having coffee...). Could you give that a go? If reflux is the problem being upright in the Moby wrap might help too?
I felt as you did, that I wasn't bonding and when dd's night time sleep suddenly became bad (at around 11 weeks) I thought I was going to have some sort of breakdown. The stress and lack of sleep probably did affect my relationship with dp but only temporarily.
But from 6 months onwards, weaning, solids, crawling all helped. It really, honestly does get better and you'll find the toddler tantrums a breeze. Dd, now 2.5 is a fantastic toddler. You'll start to bond with your baby over time, it's just very, very hard right now.
If you can get any help from family or a paid maternity nurse, do. It's a lot to cope with on your own.