There could be a great number of issues. However, a couple of things come to mind. The first is that your center shot is so far off that you have to compensate by running your sight housing too far to the left. This might happen if your arrow is kicking tail-right (which pushes your point to the left).
If your center-shot is set, arrow stiffness could be at play. If I recall, for compound bows and a right-handed shooter using a release aid, an overspined arrow will impact left of your POA.
For Mathews bows, the default center-shot distance is 13/16" from the riser to the center of the arrow shaft when it is sitting on the rest. This is just a starting point and can move later when fine tuning.
Paper tuning (HIGHLY RECOMMENDED) with fletched and bare shafts will reveal if your arrows are kicking left, right, up or down. The only gotcha is that your form and stance has to be impeccable when you do this, otherwise you will get false readings all day.
As far as the issue of running your sight all the way out to the left - most sights have a course adjustment where you loosen a bolt which allows you to run the sight as far as it will let you before it falls out of the housing. Before you do this, use the fine adjustment to move your sight to the middle. Either use the screw thread as a reference point or count the total number of clicks it takes to go from one extreme side to the other and then click it to the halfway point.
Once you do this, you can use the course adjustment to get you close and then move to the fine adjustment knob to get it to hit where you want it to. You should now have enough left and right adjustment clicks.
There's also top hat adjustments, nocking point, yoke tuning and cam shimming among others, but you need a bow vice and press to work on those items.
I would say start with center shot and verify arrow stiffness. Also make sure you are not getting shaft contact or vane contact with the cable guard, etc.
Of great importance as well is to ensure that your 1st, 2nd and 3rd axis adjustments are set correctly. This is another topic on its own but let me know if you have any questions. I'd be happy to help.
