Imagine yourself getting to a point where you are injuring throughout the day, every day. The relief that injuring gives you is VERY fleeting, lasting maybe a few minutes at best. You really cannot stop, because once you stop harming, the episodes come on stronger and stronger. Its a negative downward spiral, and stopping is next to impossible to do on your own. Yes, right now you think you can control it and that you have complete power over it, but the more you injure, the less power you have over those urges. Speaking as someone who started injuring when I was around your age and am still working through my latest remission of 10+ months, don't do it. This last episode landed me in the ER with effects that I still deal with to this day. Seven years ago I was sent to a residential treatment program for self injury because I COULD NOT stop on my own. It was so hard, but it did the trick and I was able to break the pattern. I have had episodes on and off since then, but they were more on the level of relapses. This is a fight I will have for life. And even though I still have those urges to harm, the last episode was enough for me to say "never again...."
Please, stop. You don't want to go down that road.