You have already gotten some great advice. You are closer to turning the corner than you even know!
I would like to know *exactly* how much weight your little one is putting on (pedantic, I know! - you can pm me if you like.)
Breastfeeding is a confidence trick. As the others have said, it is normal to feed at least 12 and more times a day (it's a tough gig, but it doesn't kill us!) After he has had one breast for 20 mins or so, take him off and after a burp and a nappy change, offer him the other side? Express if your breasts still feel uncomfortably full.
Why don't you just breastfeed him during the day (when frequent feeds are easier to deal with) and top him up after that last feed at night? At least for a while until you feel confident enough to phase that out?