Looks like 10' fabric length is used for the Expedition, Ultrabackpacker Asym., Hyperlite, Scout, and Desert Rat (all resulting in a 8' 4" hammock length). The only smaller hammock is the Adventure Racer. So if the ones you've been comfy in are among these models, and you want to make a "longer" hammock than one of these, perhaps you need to start with more than 10' fabric. I imagine that the method you use for wrapping could affect the length, the HH method takes up 10" on each end evidently.
measure twice, cut once, you know
sez he who dares to voice an opinion among talented DIYer's, but has yet to sew a stitch, let alone assemble a whole hammock
10' is the length I plan to make. I'll order 11' of ripstop. Minus 6" on each end after whipping = 10'