Why don't i learn as fast as other people? could i have a learning disability?

Possibly: Many people have learning disabilities that interfere with learning and many aspects of their lives. A neuropsychologist can often define the specific learning disability and recommend approaches that can help with it after careful testing.

Depends: If you just take more time to learn stuff in general, that can just be the speed you learn. To have a LD means you don't learn stuff of one type or modality as well as you do others. If you do math and other stuff relatively well, but have a hard time reading and remembering what it was about, you may have a weakness or LD in reading.Educational psychologists do testing to sort this out.