To get what most people call a powerful singing voice, I once had a music teacher tell me to bow at the waist so my head was upside down and sing. When singing you want to imagine your voice flyingout of the top of your head, andits easier when you feel like is falling out. It all sounded crazy but after a couple times it really worked.
what does the audience think of your voice?
well stop worrying and continue with the practise, best of luck, takes balls to sing to an audience.
Practice Practice, Practice .. this is also a chance for you to find new things to sing and expand things you can try. Its all part of the growing phase. Same thing happens even to older people as well.
Use a microphone