I have the feeling I am stupid, even if I am a 4.0 average at the university. Can anybody relate to this?

Peoples brains are all wired differently. Your brain has it's own way about getting things done, that does not mean you have to be perfect. Think about people with lower mental ability which are amazing with music. You have to make those neuro pathways they aren't magically there. On a side note, I also have other words representing other words without really realizing it. Do you have trouble getting ideas across?