OUr measurements of the actual circuit showed noise level in the order of several uV/sqrt(Hz). I did the noise analysis on LISO and the results indicate that the second stage amplifier's input current noise is causing most of the noise till around 30 Hz and then its input voltage noise dominates till around 200 kHz. I would work more on identifying ways to reduce the noise, would do the simulation for the loop gain transfer function and would do the stability analysis as well.

r R14 510 IN n1
c C7 1u n1 n2
c C4 470p n1 n4
r R15 560k n2 n4
r R16 560k n3 gnd
c C6 1u n3 gnd
op ISS2 op27 n3 n2 n4

r R18 1k n4 n5
c C8 4.7n n5 n7