i am me and have only ever been me

I believe this isn't something that others can understand, because by nature it is unique to me, but I will do my best to describe it accurately -

I was born into this body/this mind, and I live my life behind these eyes, with this body. I was nothing before this, and seemingly nothing after, but I exist in life, with friends, with family, with history and future, interests and ambitions, but when it comes down to it, the entire world on which I walk and breathe and live is centric to me (seemingly), because I am existing only behind these eyes and this body.

This is so weird to explain, but sometimes i get this really odd feeling of alone-ness, or like nothing that I do matters. But most of the time I live life normally, without this odd feeling...I was just thinking about it...