The problem is that she set it up and planned it. That is in the evidence.
Does a person plan a murder and sit back and wait for that one moment of psychosis to overtake them and carry out the plan? Immediately following it recovers from the moment of psychosis and is just fine.
One thing we do know, her postpartum depression disappeared in a matter of minutes because the 3 reasons for her misery are dead. Even though it took 8 months to get to that point.
I think it is reasonable to conclude she knew what she was doing.
Quite true about premeditation. Otherwise, why would a trained nurse be so supposedly incapable of dealing with her post-partum depression? Why would she go to doctor after doctor and accumulate a large mass of prescriptions?
Ms. Clancy saw a way to cure her post-partum blues: kill her kids.