If you go carbon,you will need at least .600 spine, maybe as much as .700, for good flight. Your bow, bowstring, and draw length are important variables. I had two reputable trad sources set me up with two different.500's for a 40# bow: one set shot so so, at full length, with around 225 grn points. Didn't shoot well out of my 45# either. Second set, cut to 28.5, different brand, shot lousy with 40# even with 250 grn points, and barely acceptably with my 45#. Lots of frustration, for sure.
Haven't gotten good flight yet with a set of carbons, but after months of frustration and information, I would strongly recommend talking to Braveheart Archery ( a sponsor on this site) for your carbons. He seems to have a real understanding of carbons and lightweight bows, and the right arrows in stock.
Another indicator for draw length: place a yardstick at the center of your breastbone; reach both arms straight out (parallel to floor):where your fingertips touch touch, at longest, is a good reference. You could have someone hold a tape measure for you and do the same thing. This method may be helpful, because you probably won't have settled on your anchor point yet.
If you're not overwhelmed with info yet, maybe tell us a little more about what you find your draw is, and more detail about the bow: cut to center or past center, and what string... and folks will help be more specific.