Do you use a mechanical release or finger release? If you release with your fingers, this can sometimes affect your arrow flight as the string rolls off of your fingertips. You may want to try a paper test. This may tell you whether or not you need to adjust your arrow rest from side to side. Take it to one of your local pro shops and they will put a bow square on and may be able to assist you with the fine tuning.
If you go on to you tube, there are lots of good bow tuning segments on there as well
Good luck.