Presuming you're talking about totally acoustic -
All I can suggest, as well as agreeing that light mediums should theoretically increase the volume a bit, is to play a bit nearer the bridge perhaps. That should allow you to be a bit more forceful with your playing to get an extra bit of volume, and also it will increase the attack and bring out the higher frequencies - which will give your songs more 'punch'.
I'm not totally sure about those ideas, ...but worth a try
I'm sure you'll get some more replies with more advice.