I Know That I Know Nothing

I cannot know anything with absolute certainty but I can feel confident about certain things. I know what my name is.  I know how I feel.  I know what kind of music I like. Or do I? For all I know, my name could be Deryck Whibley.  I could be feeling something entirely different than what I think I feel.  And who knows if I really like the music I think I like?  Thinking is not knowing. I do however feel confident in saying that what we know is gained through experience.  However, everyone knows everything differently because two people cannot possibly go through the same thing in the same way.  Or can they?  I can't know for sure.  I can only know that I know nothing.  I could be sitting in front of the cave wall right now and I wouldn't even know it.  Can I know that I exist? If I were to deny the notion that the world I perceive is real, could I deny that, I too am real? But then how could I, not existing, come to even consider this? Through this I conclude that because I doubt, obviously I must exist. Knowing we each exist to ourselves, because thought is self-aware does not necessarily mean we exist to each other. Nor does it mean anything else around us exists to us. Doubt is something that I feel confident about. We rely on our senses to form our knowledge, and our senses are flawed and limited, and therefore can fool us. We can only question our perceptions and confirm them to a reasonable certainty, but never absolutely.  Doubting something can potentially lead to gaining knowledge or lead to some kind of truth. We each have truths that exist to ourselves. But, is there truth that is evident to everyone? We could definitely never find, and ask every living being in the universe about even one single simple truth, to make sure we all agree. How do I know what I know? Who knows? All I know is that I know nothing.