I'm updating the software now, and making the changes to the PCB I had intended.  Right now, I've got 4-quadrant supply working, the main thing is how to handle the current limits, and getting a faster response time out of the system.  I can respond to a voltage change in a few hundred microseconds, which isn't ideal, but reasonable enough for my purposes.

I updated R13 from 75k to 50k, and put common mode correction factors into the software.  I think I stressed an output mosfet really hard though, as my correction factors are going wonky now for some reason (I'm seeing negative current when nothing is actually attached, which makes me think the PFET might be going, or the ADC ref is going weird, or the MCU got hit).  I have it oscillating between +4V and -4V, drawing 20mA over a 200 ohm resistor just fine, and am now trying to see how I can set the current limit to 10mA.  It works reasonable, but the problem is I'm oscillating around the 2V mark a lot, so I'm trying to get fast response, but not too much oscillation.  I probably need to put some kind of PID loop.

Another thing cropping up is the overall ability of the system.  The output mosfets really have a high VGS(th) compared to a lot of standard mosfets (I mean, really, what do you expect for a little itty bitty thing in a SOT23 anyway?).  As a result, the system kind of poops out at +/-10V and 50mA.  It'll do 12V if you don't load it, and 100mA if you want it at 5V, but not at 12V.

I'll still have to do a video in the coming days showing response time and 4-quadrant operation.