Seemingly, this is a very common situation. Children and teenagers alike are suffering tremendously and feel they have no where to turn. They often keep their feelings and suffering secretive, hidden and quiet. Instead of talking openly about what is bothering them they begin hurting themselves as a way to relieve their pain and cope with what is bothering them.
Based on many questions of a similar nature, I can understand why you took the approach that you did (i.e. keeping your pain and suffering a secret and hurting yourself). Your approach to your problems however is not only incorrect but it is extremely dangerous and I am very concerned about your safety.
I am glad that you wrote because it gives me a chance to teach you how to take a healthier and more appropriate approach to helping yourself. I would first encourage you to talk to your parents and be honest with them about what you have been doing and how you have been feeling. They likely have no idea what is happening with you. They may have the opposite reaction to the one that you anticipate. That is to say, they may be extremely thankful that you came to them with your situation and would be happy to assist you into therapy. On the flip side, your parents may not be understanding of your situation. This is a possible outcome. If you feel that you absolutely cannot share this information with your parents, then you can and should either go to a family member that you are comfortable with or go see your school counselor and tell them about your situation. Whoever you choose to tell this information to is less important than you actually telling this to someone. My advice is that you absolutely find a way to tell someone this information and do it soon. You, like everyone else, has a right and are entitled to get help and relieve your suffering. At this time, only you know your secret and only you can make the choice to tell someone that secret. I hope that you take my advice and share this information with someone you trust. Write again if you have any more questions.