RE: adding speed, or new bow
Instinctive shooting is all about confidence. For that matter, so is shooting with sights, but even moreso with instinctive. If you think you might miss, you will miss. So you were totally right to pass on those shots.
If you get a new bow, try shooting it for a week or two without the sights before jumping onto the sights bandwagon. The flatter trajectorymight make it just as easy for youto bust nocks at30 yards as it is at 15 with your current bow.
I don't know how you shoot, but if you shoot split finger, I highly recommend trying 3-under. Anchor with the middle finger to get the arrow up closer to your eye and gunbarrel down the shaft to aim. You'd be amazed at how accurate you can be like that from 30 yards and under.