I have a graph that looks like this. I am tasked to measure the phase margin, but the graph doesn't exceed 0 dB.

The circuit is this. The input dc level is 0.6 V, which is the problem. DC level of Vout is 0.1 V. When I change the input DC level, the graph becomes more reasonable.

What to say about the phase margin in this situation?

UPDATE

I am allowed to change input DC level now, and changed it to 0.55 V. Output DC level is 0.15 V. I measured the phase margin as ~171°.