Laura if you are relaxed before the exercise and you feel the same after the exercise, go with that... You really don't need feel different when you did it correctly. It is worrying about doing it right that is throwing you off base more than anything else. Be yourself at 14? you are in the right state to begin with

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Why not look at photoreading like learning a new computer game. You have a quick look a the basic moves, play a level and notice what happens when you make certain moves/shots. In the game you discover by trial and error what works and what doesn't. However you don't really care because its a game, right?
Look at photoreading the same way. You might want to master it someday, be nice if you could master it overnight but wheres the fun in that?
You get to refine each part of the system to your own needs as you play/use it again and again.
The tangerine technique won't make any major difference for you because nothing externally is happening. The tangerine technique is for triggering your mind into action. You just do it (like collecting extra points for lives/tools in a game) to focus your intention on the reading process. Turning 2 pages at a time happens to everyone. Practice letting it go because you can turn the book over and PR it the otherway too and it's surprising how often we regular read 5 to 6 pages without seeing what is on them either
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The fact that the pages tend to get blurry is good it means you are allowing yourself to go into photofocus as you progress. Practice holding your gaze in the center spine of the book. Looking where there normally is no text because it falls into the 'gutter' of the book.
Yes being a little doubtful does make it a bit harder. With each small success the doubt can fall away if you want it to. It's a little more difficult because you wanted to prove it works to your mother at one point. You realised there was some work involved and your wanting to prove it works is probably making you more critical of your performance at each step of the way.
My advise to you is get to know the steps of the system and then play with the whole system pretending that you have already mastered each of the steps. The funny thing is if you follow the steps you can gain excellent results even if you haven't 'mastered' each part perfectly.
Alex