Is there anyone else who does this?

I only found this site today, actually, and was really intrigued. My thing is more of a "bad habit" and isn't super-serious, but I've been researching it and haven't found anyone with exactly the same issue... The issue is this: I used to be obsessed with keeping dirt from getting under my nails, and the constant sliding of one nail under the other has caused all my fingernails to be a bit short. It became concentrated on my thumbnails. Now they are really really short, and consequentially if I let them grow out they're about half white. I started biting all my nails too, which keeps them short and gradually shorter. My thumbs are worse though. I pick at the exposed skin that was previously covered by the nail, and by now it is hard almost like a callus. (My iPhone doesn't pick up touches from my thumbs anymore, really.) And recently I've began nibbling at the skin on the sides of my nails, which makes the skin tougher, which makes me nibble at them more... The pushing up of my thumbnails is what I haven't seen yet... Thoughts?