I can't help you to identify the feedback loops, but maybe it helps a bit.
Imagine the circuit without M6,7. The gain is Au=gm1,2/gm3,4, simple diff.pair with diode loads. Diode connected transistor is a negative feedback to reduce its output resistance for example.
If you add M6&M7 the gain will increase with the added transistors, because they add positive feedback to the circuit, or negative resistance in parallel with the diodes: Au=gm1,2/(gm3,4-gm6,7). I think yes, this is a shunt-shunt feedback.
If gm6,7=gm3,4 (so the sizes of the diodes and cross-coupled devices are the same) you can see the gain is infinite. And if gm6,7>gm3,4 that creates the hysteresis.
The hysteresis depends on the gm, so not just on the device ratios, with extra tail current you can increase it.