Baby won't sleep at night (extreme case)

I seriously need help my 6 weeks old daughter has not been sleeping at night AT ALL since week 2. Literally not sleeping at all. .she goes down at 5 am-sleeps til 3 pm (with wake ups every 2 hrs for feeding and changing). At 3 pm she's DONE sleeping/napping. ..NO SLEEP NOT EVEN 20 MINUTES. .until 5 am next day. We trying EVERYTHING. going to sleep earlier (7 pm, white noise, swaddled (she HATES swaddles and screams no matter how tight, or lose u put them. .), dark room, pacifiers, etc..we fight with her from 3 pm till 5 am next day. ..nothing works...we already tried baths, lotions, massages, reading stories, soft music, white noise, bouncers, cribs, co sleepers, bed sharing, pillows, wearing baby, nothing, nothing frikin works...

Only thing that keeps her "sedated" at night is if someone CONSTANTLY SOFTLY pats her back while sitting up right on ur knee.. now, before u say reflux-we already tackled that problem. .she's on zantac already. And she does pass out from 5 am til 3 pm or so with feeding and changing breaks..

I need her to sleep at NIGHT. ..it's crazy. ..they say 6 weeks old babies sleep 9-12 hrs a night..mine doesn't sleep 20 MINUTES, let alone 12 hours. .

We are desperate...we are exausted of holding her, bouncing with her, soothing her from 3 pm till 5 am with no sleep, no naps of any kind. .straight through...

Anyone have any clue as to what else we could do?