I'm so glad to hear you're going in to see someone. I hope you find the therapist helpful and finally get some answers. Being 13, I'm not sure what the therapist's policy will be on letting your mother know about the cutting. I know if my 13 year old daughter was cutting, I would want to know so I could help her get through it when the urges came. I would be honest with the therapist and also talk about your concerns. She can only help you if you let her.