New mom struggling

I just had my baby 4 days ago. The only thing I knew for sure that I wanted to do was exclusively breastfeed. I got a spectra blue pump to build a stash so my husband could feed baby also. I breastfed for the last 4 days and it has been hell. I would feed baby and then 10 minutes later she would be hungry. I would feed again and the same thing. We have all been exhausted because she hasn’t been able to sleep. I literally haven’t slept more than 6 hours in 4 days. Last night she stayed on my boob literally all night from sun down to sun up. My nipples were so sore I was crying when she would try to feed. We had her first appointment today where I found out she lost 8 percent of her body weight because essentially she has not been eating. Lactation consultant gave us some advice on latching (she was not latching properly). I got a good latch down but the sleep and rooting has not improved at all. I pumped not too long ago and discovered that I was producing almost nothing. We just have her her first bottle of formula and she sucked it down with all the signs of successful feeding I’ve never been able to give her, the cheeks sucking in, not falling asleep on the bottle like she does my boob, and finally satisfaction and sleep. I have basically been starving my baby and I feel like the worst mom ever. I just want to breast feed her so bad. I have fenugreek I have been able to take it for one day so far. I am probably a little dehydrated from crying. I am tired. I also believe I need new flanges for my pump. It hurts my nipples very badly.