Personally, I think your handle is a tad bit short. When you put scales on it, I think you'll find that your pinky is right on the tip of the butt. Obviously size is subjective but I have found the sweet spot on handle length to be about 4-3/4 to 5 inches. This allows for your whole hand to nestle into the curves of the handle and the butt to stick out of your hand a tiny bit. It also gives larger hands a little room to breathe without feeling cramped. You've got a large mitt yourself. In the bottom photo, imagine that meaty palm with a little more handle to hold onto. Be nice, wouldn't it?
Your handle is nearly there. That last 1/4 inch feels like blowing out a wall in a tight house. Your template doesn't need to get any bigger, or even change. If it were me, I'd find that 1/4" at the ricasso. Just put that blank on the grinder and let that 2" wheel eat forward toward the ricasso ever so much. That little "guard" section before the edge starts doesn't need to be that thick. Your curvature in the handle is more than enough to keep your fingers from sliding forward and getting bit by the edge. All that extra meat before the edge starts isn't necessary, unless you just like it for the look. But there's plenty of room to get that last 1/4" and still have a guard section, It'll be just a slightly narrower one.
By opening up the handle you'll get all the room you need and won't even lose any length on your edge.
