What’s wrong with me…?

One of the thing which is the most complex to interpret is 'change'. Your brain is used to self harm. Since you no longer do it (which is a good thing), your brain will require some time, patience and well a little bit of effort from your end. I can totally understand you getting angry and pouring it out on the stuff lying in your room. It is not wrong to get angry, but it is important that you channelize your anger. If necessary get professional help, else you could try yoga. Yoga has a very calming effect and its therapeutic effects are largely underestimated. Meditation is the ultimate exercise you can practice to relieve pressure, anger and all kinds of negative energy piled in you . Try to focus on things that make you happy or distract your mind when you get angry. There is nothing wrong with you dear, you just need a direction to divert your anger. Talk to people who are close to you and never ever lose hope. Doing something right needs a lot of courage. Going back to the old ways of cutting yourself may seem to be very easy, but there is something which tells me you are very strong. I hope the best for you. Good luck :)

Do you have access to therapy? If so, you should seek that. If not, a good way to calm down May be to close your eyes and breathe, count to a number-how ever many it takes. Other ways can be yoga, writing in a journal each time this happens write how you feel and what you did, why you think you did it, etc. exercise releases endorphins so choosing an exercise that works for you is a good idea. Just try to find ways to cope that works for you.

I would seriously suggest to you to see a therapist and deal with your pent up anger. May I ask what was the reason you started self harming?

Well I think that this is your body's way of coping with the sudden stop of self harming (it's like your body was dependent on it and now that you stopped, it has to find another way to cope). I think you should talk to your parents about it and see if they have any way to help, go to anger management classes, see a therapist or someone that could help you understand more about this and just surround yourself with positive and optimistic people because, trust me, it does make you feel good and happy. Just remember that if your ever feeling really angry and wanting to destroy your room, get a stress ball or hit a pillow. Good luck and if you want to talk I'm here :)