Trying to understand my printer

I recently built an Anet A8 printer and loaded on Skynet firmware 2.3.2 after about a month of playing with the stock firmware. After homing for the first time, the printer made its way to the upper right corner and made it home. I played with the settings until it homed in the center of the bed so my prints would be centered. Im trying to understand the distances that are in the arduino coding. The bed size on my Anet is 220x220mm but the center of the bed when I home the machine is at X 92 Y100 and when hitting the endstops the numbers are X-10 Y-30. How are these numbers configured? The way I think about it is in a Cartesian plane where the min endstops would be X0 Y0. When I move an axis by 10mm the head seems to move more than 10mm as well. Am I thinking about this all wrong or is something configured wrong?

Well if the prints come out right then this configuration works.
Sometimes firmware is adapted from other stock solutions to the specific machine.
Another parameter you can check is the step size for the steppers.
But first of all, see if the prints come out well.
If not, look for new firmware and avoid beta-releases by all means.