From the sounds of the hit, you probably took out one lung and the liver. I wouldn't suggest taking this shot though however since it will not give you a clean quick kill. I would expect a little more blood then you described though. Were you using a two bladed head? I have also experienced poor blood trails sometimes with the two bladed heads and now use them only on game where I really need penetration like elk or moose. On deer, I usually use 3 or 3+ blades heads. If you would have waited longer (about 5 hours), I bet you would have found your buck in his first bed.