1st of all please relax and dont b too stressed out as tht will hamper your milk output
Yes the flat nipple seems the problem here, u can try syriging technique
Yes nipple confusion does happen
You need to get consulted for proper breastfeeding technique
Meanwhile u can express/pump milk and feed the baby, if milk output is less u can start tab lactare one morning evening or use formula feed 30ml water and 1 scoop powder make sure this concentration is maintained
Next Steps
keep a watch on the urine output atleast 6-7times in day time
Health Tips
keep urself hydrated and dont panic