You may sound more confident by simply playing louder. Try 10% louder to start. see what reaction your playing has on listeners. Another take on fake it to 'til you make it. Secondly, crescendo when the melody rises and diminuendo when it falls, unless the composition or arrangement says otherwise. This should help remove some of the timidity in your playing.
Revised August 2022
You've got to learn your instrument. Then, you practice, practice, practice. And then, when you finally get up there on the bandstand, forget all that and just wail.
I'm a professional pianist and music educator in West Toronto Ontario. I'm also a devoted percussionist and drum teacher.