Here are some points to consider.
1. Brace height, start with recommended then lower 1" and start, shoot and raise until you find a point where it sounds and shoots best. Twisting a flemish string 10 turns will raise Brace Ht. about 1/4 inch.
2. Check spine chart. See shooters forum and topic of interactive spine chart vs spine selector for links.
3. Shoot thru paper. Set up a box frame with paper (newspaper or heavier). Set at shoulder height in front of bales or backstop and stand about 10 ft. from paper and shoot a fletched arrow and watch for direction of tear. Then bare shaft. If the point is low and tear is up, then lower the nocking point. Continue until it is leaving just a hole.
4. To determine if the arrow is hitting the shelf, put a little shaving powder, or baby powder on and around the shelf.
5. Check your nocks, if they are tight, use sandpaper to open, or switch to a different nock.
6. Recheck your form and equipment.