Very nice bow with good tiller. Sounds like you are shooting quite well, especially for a beginner. With more practice your groups will tighten.
Try shooting one arrow at a time then retrieving it before you shoot another. If you can put it where you want it, you are shooting good. Having a group of arrows in the target at one time can be distracting for me. By shooting one arrow at a time its just me and the target. Pat