I have always had a problem with my arrows hitting about 2" to the left of bullseye. It might be 2 out of 5 and sometime 5 out of 5. I recently got a sight that had a bubble level on it. I started making a point to be sure that the bow was level before I fired. I was almost always leaning just off center before I leveled it out (even though if felt comfortable before I looked at the level). Now my shots fly straight and all hit exactly where I was aiming. This may not be the same problem you are having but I use it to point out how an unconsistant form can make that kind of difference. If it is happening with every arrow but at different times, I bet it is your form.