It looks like you will have shoot trough between the "A" and "B" FET's.
The boxes around your circuit sections also make your schematic more difficult to both read and maintain. I'm wondering, how many times have you re-drawn those boxes?
I'm not sure about the rest of your schematic. Your opamps look like square black boxes, I don't even look at such schematics.
Reading though the other comments, there are also already plenty of other flaws detected.
It also looks like you are overthinking it. It's easy to make a 100mA current source or sink with just an LM317 (or LM7805 or similar) and a resistor. With 100mA you also already have 1mV over a 10mOhm resistor and simple DMM's usually have a resolution of 0.1mV, so there is no need to amplify your signal at all.
With an external power supply, a simple current source/sink and a separate DMM you also already have a 4 wire measurement that eliminates wire resistance (Or you can explicitly measure that too of course). And you can of course also check your current source with the current range of your DMM to verify if it still works.
Some years ago I read a CircuitCellar (#314) article about a milliohm meter, which was quite cleverly built. It's quite simple with a small uC, an ADC1115, a display and a bunch of passives. I attached the schematic, but the rest of the article is worth reading too. They claim a resolution in the micro ohm range, which seems reasonable as the 1115 can measure quite low voltages.