Why does this growth on my finger never go away?

I'm going to call it a "permanent callus" because I don't know what else it could me. When I entered kindergarten at age 5 we started learning to write with pencils. I had a bad habit of pressing down really hard with the pencil to the point where it would hurt. It was a surprisingly difficult habit to break. Pressing down on the pencil made a callous type growth develop on the spot where the pencil would lean on my middle finger. When I stopped writing by hand for my homework in the 3rd grade, the callous finally began to shrink down again.. BUT it never shrunk down entirely. I'm now entering college and the mini bump is still there even though I don't use pens or pencils to write anything. So what is this a permanent callous? or is it like a bunion on my finger? Is it because I was so young when it first developed?