I've seen a lot of different definitions on self-injury. But the points that almost all have agreed on are:

-It's done to help cope with some emotion
-It is purposefully causing harm to your body
-It is not done for decorative purposes only (such as body piercing)

Some people include drug and alcohol abuse, unsafe sex, etc. in their definitions. As Rapunzel said, it has a lot to do with intent.

I would agree that what you are doing is self-injury.

Take care!
SweetCrusader

"Blessed be the cracked, for they let in the light"
-Author Unknown