Sleep training 1-year-old

Has anyone been successful at sleep training their one year old? My son is sleeping with us in our bed and lately he's gone back to only wanting to sleep being nursed. He will not fall asleep any other way and he wakes up A LOT at nighttime and the only way to put him back to sleep is on the boob! No self soothing here :( He was getting better and I was getting decent sleep but this all started up again. I'm pregnant again and due in June. I would like some good sleep before next baby arrives! Any advice appreciated!