I would just like to add a thought here. Being considerate and appropriate with your volume is great. I look for that trait in musicians i get to play with. It shows a "presence" of mind to the situation you're in. However, there is a difference between being considerate/appropriate with volume, and being timid. Don't be timid. The other musicians want to (and need to) hear what you are playing. If you play the greatest note ever played, you want it to be heard ! Turn it up a little.