Reply To: how does Hashem want girls with good voices to use them?

Hashem gives us our talents so that we can help other people with them, or otherwise use them in our Avodas Hashem. Loving Hashem is one of the six constant mitzvos. Perhaps while you are signing, instead of thinking about how good your voice sounds or whatever (showing off, as you mentioned), try to use your voice to arouse your heart and mind to feel love and awe for Him. Or perhaps you could be a voice teacher, helping others connect to Hashem and gain self-esteem through improving their singing?