I have just weaned my 16month old, he also fed to sleep day and night. I started with the day sleep, I made sure I had a "real" bra on - so he couldn't get to my boobs and just said "all gone". I cuddled/held, while he screamed blue murder and I felt awful, but he would eventually calm and go off to sleep. It took a few days and then a week later did the same for the night feed. It was so hard not to give in and feed him, but I didn't want to give mixed messages so I stuck with it and just spoke calmly, sang lullabies and cuddled. I kept all other sleep cues (music, sleeping bag) the same.