Concernedn, I think it would help the approachability of your post if you refrain from using all capitals when replying...it is the online equivalent of shouting. Lol.
Unnamedny, I think you have some valid points, but it seems to me like concernedn is approaching the subject from a different point of view.
OP, if you break it down to what is sinning and not sinning, then your argument that the impurity of your thoughts during masturbation goes against your religious ethics and morality is completely valid.
What if you were thinking those thoughts about your wife? The act in itself is not what is wrong, and is not what you need to limit, if you should feel the need. It's the nature of your fantasies, probably.