I am a cheerleader and I can not deepen my voice. I need help to not sound so squeaky and girly.
You need to develop more chest resonance to add depth and volume to your voice. To do this without hurting yourself takes great care and knowledge. It is most advisable, especially at your age, to work in person with a teacher or coach. If there is no one in your area you might want to try a phone session with a professional coach. If you are a tiny person, your voice will never be as deep as the voices of larger people so keep that in mind too.