You can put weight tubes in carbon arrows. I like to have closer to 10 gr. per pound of bow draw weight, so yes, you are a bit light. More weight will give better penetration and a quieter bow. You could also try adding brass inserts (50 to 100 grains). The 100 grain insert would get you to 10 gr/pound. It also puts the weight forward, which is recommended by Dr. Ashby.
Personally, I have trouble getting decent arrow flight with carbons. My preference would be cedar, aluminum and carbon, in that order. Actually there may be other woods that would beat out the aluminum and carbon arrows, but I haven't tried anything else. Cedar works for me.