i feel really bad for you that you have been disappointed so many times. maybe there is one factor in your regime that is missing or something? though since you have been working on it for so long i am guessing this is probably not the case.
i cant imagine how you feel, but i know i have had a lot of issues with 'the mirror'. from a spiritual perspective, i have taken so many years trying to get over these issues and finally let them go. it has been a lot of hard work, but i have got to a place where i can honestly say i have worked through and overcome them. they will not ever completely go away i dont think, there will always be traces of them in my memory at the very least. maybe this is like my scars too.
it is only since i have laid these issues completely to rest that i have actually started to see things turn around. im not talking psychologically (that has been a gradual improvement) but the actual material fabric of the problems in my life is changing before my eyes (again - like my scars!). i attribute this to the spiritual truth conveyed in the parable 'the three loaves' and that is this: 'once you let go of this material life and desire only the life of the hereafter, God will set right your affairs of this world and guide you on the straight way to your reward in paradise' amazing!
for me, the only way out of unhappiness was faith. it can be the same for you if you choose! it is possible that no matter how bad things bother you, or how terrible your life is to get to a place where it does not matter in the slightest. no thats wrong - it matters even more because you are grateful to have experienced something that brought you closer to God and made you a better person!!
good luck to you plasticat! remember even if you cant change things on the outside you can change things on the inside and that is better in so many ways!