Is It Wind, Reflux or Normal?

My 18 day old daughter appears to have an issue bringing up wind. So far she doesn't appear to be a cry-ey baby but past two days, she's been clearly uncomfortable: arching her back, bringing up knees to belly, wincing while asleep, randomly crying out in a short scream before stopping, rooting, sucking hard on fingers/dummy. The screaming out is heartbreaking. I wind her for like 5-10 mins and she'll burp, other times I can do it for 20 min and no burp. She gets hiccups regular and vomits every time I lay her down for a nappy change after feed. Vomit is pure milk, totally undigested meaning it's coming straight back up. I sit her up for 10 min at least after feed - what am I doing wrong? I gave her 2oz of cooled kettle water which seemed to help. Any tips to what I'm doing wrong? Or what's up with my LO? Does she have reflux? Normal wind? Am I feeding her too much (3-4 0z every hour & half)? Colic? Please help