I make lots of short ones, so I'm not saying you MUST go long, not at all. Depends on your goals with each stave. I am simply saying that it is easier to get a shooter from a longer piece of wood than a short one, and if the goal is a shooter, longer is easier. No one started making self bows however because it was easy. The rule of thumb I passed on to you earlier is just that, a rule of thumb. It can be bent, twisted, broken or ignored all together, and as evidenced by the short Molly that Half Eye mentioned, with enough skill and luck you can do all kinds of things. But the rule is there for a reason. On the average your odds are better if you follow it. This is a great place to learn this craft, and you will find no shortage of people willing to help with advice and critique. Post what you have early, and solicit advise on what to do next. You will get varying opinions from lots of folks, then just pick what seems right and get after it. Looking forward to seeing what you come up with.
I want to add that no matter which way you go, long or short, good tiller is a must on either and especially critical on the shorter bows. Your tiller eye needs some refinement. I would suggest getting you a straight edge, 4 inches long or so and working your limbs into shape slowly, using the straight edge. It alone will keep you on track to a serviceable if not enviable tiller on this one.