That might be a learning disability, but it might not be. No one can honestly answer your question specifically for what's "wrong" with you. I'm not even sure the word "wrong" works. Here's why.
I never had a learning disability per se, until I became a senior in college. All of a sudden, I couldn't pass a true/false quiz when I knew the information down cold, if my life depended on it. Looking back, I see all that happened to cause that result, but even back then, I knew what was wrong. I was freaking out! (How's that for a scientific label for a description of a real problem? lol) I had spent 16 years in school by then and out of those 16 years, I knew what I wanted to be when I grew up for 14 of those years. I wanted to teach high school English. A couple of health problems developed that summer, plus my adviser told me I could graduate, but I couldn't be certified to teach. My 17th year in school, all aimed to do one particular thing in life, and I was flat out denied that one thing I wanted. Too late to pick another major. My dad isn't the kind of parent to pay for college past 4 years and I had no idea what I wanted to do, even if he did let me keep going. Looking back, that was a good thing. Remembering back, I thought my life was over.
If they had such diagnoses back then, they might have diagnosed me with some kind of anxiety disorder, and that would be accurate. Can't get much more anxious when you're 21 then to find out all the work you put into the previous 16 year wasn't going to get you what you wanted and you had no idea what else you could want.
But, I'm wondering if you aren't having freak-outs of your own in school. Again, I don't know.
But there is one thing I do know. (Three years of schooling to become a teacher, does give some thought to how to learn. My brother has dyslexia, so I also spent all that time watching him struggle with school, and later on, I found out dyslexia runs strong in my family, so a lot of my cousins and their kids struggled like my brother did.) Some people just don't learn stuff in the traditional way. That doesn't necessarily mean they have a learning disability though. Sometimes "the cure" (and I put that in quotes, because there is nothing to cure. The brain works fine, it merely works differently) is as simple as going to one of those tutoring places to relearn how to study. "Sylvia" is the only commercial for one of those places that I can think of right now, but if you watch TV, I'll bet you'll see a commercial for something like them near you.
See if your parents are willing to help you that way. If that works, you don't need to worry about going through all the steps to find out if you have a learning disability. After all, the only purpose in being diagnosed is to find ways around it, so, if you find a way around it first, you don't have to worry about slapping on a label.
Oh, and if you're wondering? My teacher worked with me, once I told him what was happening. I really did learn what I needed to each week. It was the test that freaked me out. I over-thought it and couldn't control the freak out. Instead, once a week, I walked into his office and told him everything I knew about what was taught (or read) that week and I aced the course, despite the freak out. Teachers are also great at helping students, if the student is willing to tell them they need help and why.
And your parents? They probably do hear you, but they're parents. Parents tend to freak in their own right when thy find out something might be wrong with their kid. They want only good things to happen to their kids. Some can't get past that freak out anymore then I could get past mine. If you give them an idea of what you want to do about it, they'll probably look relieved and do it for you.