It happens to us all, this past Friday I was hunting and shot a scrawny 8 pointer following a massive 6 pointer and a doe the 6 pointer was chasing.
Where I hunt it has to be 4 points or better on one side, such a shame...anyways...
I took a what should have been an easy 50-60 yard shot and found bone, muscle tissue, and lot of white fur.
Long story short, after 200 yards of criss-crossing and circling blood trails we found no deer and the blood trail faded out.
Deer can survive with three legs and injuries that would surely stop any of us mere mortal humans haha. They sure are tough so dont hold it over yourself too much. So long as infection doesnt kill it you can be fairly confident the deer will be around next year (granted I dont know what kind of meat, blood, and color fur you saw...) however deer are, as mentioned, incredible at surviving.
It sucks but keep going! Dont beat yourself up over it
I am an ethical hunter but I wouldnt track a deer for days unless I was sure it was a mortal wound, The buck I supposedly leg-shot did not have enough blood lost or any other circumstance that would lead me to believe that there was a dead deer.
Keep on hunting!