Hello, we've been dealing with this problem for almost four months now…

Hello, we've been dealing with this problem for almost four months now. We only use G-feeding and have trouble with sleep. He only sleeps if I'm nearby and is sucking on my breast, so he might sleep for an hour during the day but if I'm nearby, he will suck on my breast constantly. Only when I leave him does he wake up. Has anyone else experienced this and what did they do?