My guess is that stuttering is a purely psychological illness (I mean blocks, I don't know how it is with tonic stuttering) in that it is purely physically possible to just talk, read, etc. Another thing is that it is so strong that it can involve many parts of the body and send very strong anxiety in such a way that nothing helps to stop stuttering despite of everything. I think it's as you described, it's a 'bad habit', my therapist also talked about it, but getting rid of it is something out of the realm of fantasy (notice I'm not saying impossible). You don't remember how fluent you were, and in any conversation on a subconscious level you will refer to stuttering, with this, if I may say so, firmware, there is no cure. You have to change that somehow. In my opinion, nothing helps more than constant practice (talking to strangers for several hours everyday). I know it's hard to implement. But I guess this is the only way to get rid of this curse. I sympathize with you and hope for your recovery and resolution of your problems!