AndriDem,
It's a shock to the system to think that you could have been doing it easier a lot longer. Be mindful of this and be kind to yourself. It's easy to pull back into old reading habits at this point as what you call doubt is the conscious mind not being able to accept it doesn't have to take so much control when it comes to reading. It's trying to negate the experience that you are learning faster. The shock hit me so hard, that I had been reading the slow way for so many years and I could have been PhotoReading and got a lot more from my reading, it was like I didn't want to believe it. It took me two weeks to get over it and really start using the system I know there are others who haven't. I had to acknowledge the reason I had not been using this method is I didn't know about it and no one taught me. I'm glad I got over it too.
AlexK