I don't know how old you are, but personality disorders should not be diagnosed until someone is an adult. For obvious reasons, you are still growing and your personality is still developing.

There are some "similar" disorders that are diagnosed in kids such as conduct disorder and oppositional disorder. Some believe that these disorders are developing personality disorders. However, they are usually more related to Reactive Attachment Disorder and Attachment issues.

If someone diagnosed you as BPD and you are younger than 21, I would get a new doctor.