Sorry to hear your guidance counselors, teachers or principal do not help you despite your repeated attempts to ask them to intervene. I suggest you talk to your parents again, who love you and know you best, tell them that you want to be rid of this bully situation but do not feel comfortable fighting. Perhaps another heartfelt discussion with them will produce a good solution.
That said, in my opinion, there is a difference between fighting and self-defense. If someone is slapping and pulling your hair, why shouldn't you protect yourself? Push her off of you, pull her arm off you, shove her away hard so she lets go of you. She is hurting you, she is being violent, and there's nothing wrong with defending yourself. Talk to her loudly and firmly when you protect yourself, tell her to stop, and show her you mean business. In my opinion, the more you let her slap you and hurt you, the more encouraged she is to do it because so far there has been no consequences--not from you, not from her parents, not from the teachers or the administrators.
Another option is to switch schools. You can also take martial arts classes to give you more self-confidence. Not that you would knock down the bully with a karate chop--but they do teach you moves on how to block an incoming fist or leg and they give you that confidence that may help you stand up to a bully.
Bullies like easy targets. But if you make it difficult for them to pick on you--by standing up to them--they may decide you're not worth the hassle and move on to someone easier.
I don't know of any parent who would ENCOURAGE their child to hit someone...That doesn't resolve anything.
