I also think that you shouldn't go on with this. Even though this is the beginning. If you don't stop now, It will be very hard to stop in the future. I know from experience. Try alternatives like writing on yourself in red pen or using ice to feel the pain. That's is what works best for me. About your step father, try talking to him about how you feel. Parents (and step parents) can be extremely annoying when they want to control your whole life. Tell him you need some space and what you need him for. Hope this helps!