I wouldn't feel safe feeding a baby in an Ergo if i was really tired (like overnight). Whether you co-sleep or not (and i didn't have bub in with me overnight when she was very little unless we were the only ones in there), you need to be and feel safe.

If you can learn to feed in a carrier it is a great skill to have though! I am not very good at it.

Falling asleep feeding bub on the couch can be more dangerous than safe co-sleeping. Can your partner take bub for awhile so you can get some sleep? Can you nap during the day? It does get better, you just have to work out best way to survive these early weeks.