My son was trained for pee before he was 2.5 but he would wait till nap or bedtime when I put a diaper on him to go poop....I was having a heck of a time then it was like a light went off and one day he started going in the toilet. I have heard some don't like to go in the toilet cause it "plops" and either scares them or gets them wet and its easier to get them to go in a potty to avoid that and ive also heard that a potty is more like a squatting position and therefore more natural. at this point hes just being stubborn cause he says "I don't want to" what if you threatened him with a time out ? would that work for him? I had a dcb that knew when he had to go but couldn't be bothered and was 3.5 so I put him in the time out circle and miraculously he remembered to tell me after that every time ....it only took once. when they know they have to go and choose not too then I think you have to give them a deterrant (time out ect) but when they are younger and truly don't know or are just learning then I wouldn't never give a time out but at his age and since its been months maybe you need to step up the expectation.