I understand both sides of this -- as a worship leader myself, I am actually most comfortable worshipping when I'm actually leading the worship. But that is what God gifted me to do, so I SHOULD feel comfortable doing that.
With that said, that does not mean that I'm NOT comfortable when I'm NOT leading worship. I think it's truly important to learn to worship without the instrument in your hand. After all, you may not always be able to have that bass in your hand. So perhaps it's a good idea to put the bass down for a while and just focus on your heart during worship.
Let me also add that putting one's hands up in the air is not an indication that you're truly worshipping God. Yes, oftentimes we express our worship by raising our hands, but it's not what we do outwardly that indicates whether one is worshipping in an authentic manner -- it's the inward expression that's important. Some folks, like my hubby, for instance, just doesn't feel comfortable lifting his hands, clapping, etc., but that doesn't mean he's not worshipping in spirit and in truth. It's all about the heart, not the hands, head, voice, feet or any other outward part of our bodies.
Finally, as you're worshipping (without your instrument), make sure you enter God's presence with an attitude of prayer. Despite the fact that we most often worship corporately, corporate worship is in actuality the sum of individual worshippers. Talk to God during your worship time and don't even think about what others around you are doing. You may want to spend some time worshipping God alone and not corporately. Then once you gain that confidence in your own personal worship, you will feel more comfortable worshipping God in a corporate setting.
Thank you for your honesty in your posting. The best way we can express our love to God is to worship Him. Worship is, indeed, THAT important. I wish more people took it as seriously as you do.