Where is my buttercup?

I'm occupied
By things inside
That coincide
With the outside.

To show this mess,
I must confess
That I am less
When at my best.

It numbs my mind.
One of a kind.
Adamantine-
Please close this blind.

Always distracted,
Never well-read.
I've always acted,
It's me I dread.

How am I known when I'm only bone.
Not even grown, and left all alone.