I can feel your despair and unhappiness. Whilst I can't say I've tried all those diets, I know the feeling of feeling so down about my weight that I dont know what to do, and can't see any way of ever losing the weight. It's one if the worst feelings in the world, but you can turn things around. I don't profess to have all the answers, if I did, I wouldn't have reached 26st! What i can say, from my own experience is that you have to be absolutely commited to losing the weight, that means in a choice between an unhealthy meal and losing weight , 95% of the time losing weight will win. I don't think it matters which diet you choose, as long as you commit to it. For me, as I needed a change of lifestyle and to learn how to eat healthily for the rest of my life, I feel I have to follow a calorie controlled healthy eating plan. Whilst it may not be the quickest, every day I learn a little more about being healthy in a way I can sustain forever.
If I can do this, you can too. You just have to believe that you are going to reach your goal and take one day at a time. This is the most amazing site for support and encouragement, and keeping a daily diary on here is also a way of tracking your feeling as well as your daily food intake. It's helped me to work through so much emotional baggage around my food issues. Things I would have had any idea about before I embarked on my journey.
Please don't despair, as my grandad used to say ' where there's a will, there's a way' and once you find your will, I think you'll find your way.
All the best, I'd love to see you start a daily diary and help you along your way x