I agree with MR.
My ds had issues at that age. He was cutting down how long he spent on the boob, and tbh - he was quick at it before the problems started. Food wise, it's all up to you and your baby.

My ds weaned totally out of the blue as well. He was 15mths. I'm not sure if it was what was going on (we had just moved), or if he just decided to stop. He was down to 2 feeds (a breakfast and to sleep at night), with the possibilty of a lunch feed, if only a small one. When he weaned he had a normal day, that night he had some, then just rejected me. He was comp fed with bottle. He was right then. The next day - nothing. Totally random.

All the best! Stick with it!