Dream interpretation doesn’t hold much scientific validity. It’s not like people think where dreams have common symbols or give us some deep meaning to be interpreted by a psychoanalysis. The current psychological view on dreams is that they’re only as important as you value them. They allow our minds to creatively solve problems, imagine things that can’t happen in reality, or assemble information that we gather during the day. Your dream may just be random, or maybe it’s the expression of some deep sadness that you’re not letting people know about. Cutting is usually a sign for help, so it may benefit you to talk to someone about it. Preferably a parent or some other adult. Or, it could just be random neurons firing. Only you know how you feel.