You are missing a big one here. 7 speed road bikes have 126mm rear drop out spacing, 9 speed have 130mm.
You are going to have to change your freehub to a 8-9-10 speed compatible one and re-space the rear axle to 130mm and re-dish the rear wheel (or get a new wheel). Being a composite frame, you will need to spread the drop-outs every time you install the rear wheel, I'll leave others to argue whether its going to damage your frame to do that.