Help! Therapy. Please Read.

Okay so I'm currently 16 years old and I've always had points where I just get really sad but I've never had anyone to talk to. Lately I've had some family problems, and personal problems which have really just made me super sad and feeling drained and just emotionally done with everything. My problem is that I don't know how to fix myself and I want to see (hire) a therapist but my parents don't take me seriously. They think therapists are only for crazy people and they see no reason why I should need a therapist because I don't really share the full range of my emotions with them. Me and My mom aren't close enough for me to tell her about my issues and I don't really have any friends so who can I talk to? How can I convince her to let me see a therapist?