Pastor,
Your post is a little confusing, so I want to make sure we all understand where your arrow is hitting. Nock high is not the same as your arrow hitting high. Of course that is obvious, but your first post says that "your arrow is hitting high". 1/2" is about right on the nock height. To be honest, some archers NEVER correct a little nock high. That is totally acceptable. I would RAISE, yes RAISE your nock to 5/8" and see if the nock high result improves or gets worse. My guess is that 5/8" will be a little better. If it improves by going to 5/8, then go up to 6/8", 3/4", etc.(your shooting style may just require a nock height on the upper end). Once the improvement reverses and your arrow is WAY nock high, you can then rule out going higher and start moving your nock back down towards 5/8...or wherever you achieved close to perfect nock results. This can definitely be confusing. The fact that your left/right "fishtailing" results are good at least confirms that your form is good enough to achieve decent arrow flight. So, feel good. Good luck. Your almost there, Pastor.