Each therapist or psychologist have different goals. Each stutterer also has different goals. One stutterers has a goal to reduce social anxiety, another one wants more control over speaking, another one wants less control (which is what I recommend: subtract over adding control) and other stutterers want to focus on secondary behaviors. Each therapy applies a different strategy or method. Each psychologist applies a different treatment or modality. You already practiced breathing exercises and slowing down (which is called intervention aka adding control). So, my suggestion is to try the other approach whereby we learn to subtract control (and stop with intervention).