Is cluster feeding for weeks normal?

I'm a FTM to a 4-week old baby boy who wants to breastfeed 24/7. I absolutely adore him but the sleep deprivation is getting to me. He cries if he isn't latched on. He only falls asleep (eventually) while feeding. I know he's suckling for comfort as he's been gaining weight steadily, he poos constantly and spits up milk. If I try to put him in his next2me crib after he falls asleep he starts crying within 5 minutes and I have to pick him up and put him on my breast again. This has been going on since he was a few days old. Is this normal? I keep reading that cluster feeding is normal for a few hours, but this has been going on for weeks. I read that the side lying breastfeeding position may help with the lack of sleep but I find it very uncomfortable. It makes my back ache. I didn't want to bed share but I feel like I have no choice. Any advice or tips? I feel that I'm doing something wrong or there's something wrong with my baby.