I can't answer your question as to what type of disorder dyslexia is, but I can tell you that people can overcome it, and work with it as they age. But those with dyslexia are also going to see signs of it becoming difficult again as they age.
Since I am also dyslexic, I have gone through the same things you described. As a child in school I was labeled lazy, or having a short attention span. I not only transposed letters, but also mixed up letters and numbers. I couldn't see the difference between an E and a 3, or a L and a 7. I never understood when they tried to teach me spelling and math why they used the same letters and numbers for both? I had a teacher in 1st grade who thought she'd help me by putting me in the back of the class with a mirror on the wall to look at the blackboard backwards! It only worked to make my learning more difficult, and set me back further. I struggled, and was pushed along with nobody diagnosing the problem. When I reached 5th grade I had a male teacher (Mr. Wells) who I am eternally grateful for! He didn't know what it was, but told my parents I was not lazy, or inattentive. He knew I had some sort of reading disability, and asked my parents if I read at all at home? He suggested to them that if I liked to read anything, then they should encourage that, and get me as much reading material as possible in whatever form I enjoyed. That happened to be comic books, and the local thrift stores had them stacked to the ceilings for a penny a piece! My father took me down there every Saturday, and I picked out 10 comics. I had comic books stacked 2'-3' high all along one wall of my bedroom, and by the end of 5th grade I went from being pushed on to the next grade, to being in the top of my class. Mr. Wells opened up a whole new world for me, and it was like somebody turned on a light switch in my brain that year! I regretted moving on to 6th grade, as I was afraid what might come. But his help made the change that allowed me to succeed through the rest of my learning years, and nobody noticed my dyslexia after that.
I never learned of dyslexia, or put a name to what I had until I was in my 30's. And never talked about it, because I was embarrassed by my early learning struggles, and the way teachers handled it. But I finally reached a point where I realized that not talking about it didn't help others with the same problem. Now I try to talk to young parents who have children with some form of dyslexia, and hope I can encourage, or help them help their kids.
I'm in my mid 60's now, and although I became an excellent student in middle school and beyond, my spelling takes more thought now. I also have to occasionally struggle to think of the correct words to use. I still read a lot, and hope that it will help as I age to not revert to where I was in my early years. Keep your chin up! There's not much we can do, but work with it, and not let it bother us too much.
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You're good!
