How to decouple a negative feedback loop in DC?
The control-range for gain is far too large. And the rin of Q2 needs modeling.

Add 50Kohm from base Q2 to ground. Make R8 (in series with the FET) much much larger, perhaps 1MegOhm.

The Ic of Q1/Q2 is 0.1milliAmp. reac is 0.026v/0.0001Amp = 260 ohms; scaled up by beta, that likely is 260*100 = 26,000 ohms. So you need Darlington diffpair.