If you have insurance coverage, the first place to start is with the insurance company to find out what they cover. If they can connect you with a gender therapist, the therapist should be able to refer you to somebody who can help. Often there are special programs for people your age. The can be found through your local LGBT center. You will need to receive some form of therapy because of your age. Informed consent is only possible after age 18 so that leaves the planed parenthood route unavailable to you. You will need to have your mothers permission and involvement and if you can't get it, you are pretty well stuck where you are. If your mother isn't willing to work with you, that needs to be the first thing you address.