Wow..if I was only 6" high at 70 yards...I'd be pretty happy !
I know what you mean Brad. So many things can change your arrow flight. This makes it difficult to assess on line.
Maybe try taking some video of you shooting in various poses and positions and watch yourself in action.
Sometimes we change the position of our hand (heel the bow or use a higher wrist hold), or we squeeze harder one time, or we anchor ever so slightly different if we are, say, seated vs standing, or we hold our head differently in the same circumstances. From above, or from below for that matter, the arrow travels a shorter horizontal distance to the target than it appears and naturally tends to hit higher, hence the need to aim lower from a treestand....all these things could cause you to shoot high.
Or, maybe you just need to keep at the practice for a while more. What really helps me is getting into the woods, or even the back yard, and just roving, one arrow only. Start short and after you get into it, any target range you chose is fair game. I try to just have fun and just forget about whether I hit or not. Eventually it all comes around for me.
Stay in there.
ChuckC