If you haven't done it already, use a dial indicator and see if a 1" move results in one inch of travel on all three axis. if not use the mach3 wizard for setting the steps per inch. You are off by .022 which is a large amount.
On my Taig, the steps per inch should be (according to the math) 16,000/inch as my drive is set to 1/8th step but my steps per inch needed to be adjusted slightly to some weird number like 16,023.54 to make it move exactly 1 inch.
Since you haven't mentioned it, I will assume that you are not using g41/42 to set cutter comp.
On my bridgeport, my 5 tpi screws should give me 20,000/inch, but they are actually metric which gives a real weird number when using inches, so the math is correct, but only if you know the actual numbers to input.
Once you have the dial indicator moving one inch when you try to move one inch, I would try cutting a square in some scrap material as you can hand code it really easilly. The move on to a circle.
The other thing to check, and it has caught a lot of people, is to use a second measuring device to verify your measurements. One guy here on the zone was going nuts with an odd table movement dimension and found out that his dial indicator had a cyclicle error and once he had a good indicator, he had everything perfect.
Mike
Warning: DIY CNC may cause extreme hair loss due to you pulling your hair out.