Depression doesn't discriminate - and you don't always need a 'good' reason to cut either, sometimes exhaustion, stress, boredom, whatever, is enough to trigger an episode. You realize it's not helping you though which is a good sign you want a more healthy and effective coping mechanism. Seeking professional help can provide that. Don't be afraid to speak up, your mental health is not to be gambled with anymore than you would your physical health. Good luck.