If your parents are paying the bills so you can see the therapist and pdoc tell them. There are books available that are listed in the recommendation section that you can buy at the local bookstore, and it can become a learning experience for you and your parents. If you really need a second opinion and would like to start treatment over the summer, tell them, unless you are on a separate insurance plan and you work and pay for all of this yourself.

You don't need to tell them everything that is going on in your life, but I am sure they would appreciate if you explained why you need a second opinion and if they'd take those steps with you.