There could be LOTS of reasons ranging from bow tune or bow fit, to form, to just need practice.

My shooting seems to respond the best to limited practice, to much and it can be bad. I shoot 3-5 times a week, start at 20 yds on my block, shoot 3 arrows at a time, at 20,30,40,50. Then from 50 back into 20except this time at the 3D target. That's it.

I have to ask, how tall are you?? You say you have a 31 inch draw, which is possible, but if you are under about 6'3" or so, its suspect to being to long.

Being overbowed is also a big accuracy killer, back the 70 lbs down a couple of turns to see if it helps.

Also, number your arrows, its possible that they arrows are out of tune. If the #3 arrow (for example) is always the flyer, turn the nock to see if this helps, sometimes an arrow just refuses to play nice with the rest of them.