At the outset, I wonder why you have preferred consulting a psychiatrist
rather than a OBG doctor for her post-menopausal symptoms ?
Did you consider HRT
for her yet. If not - do it now. Ask the OBG doctor.
SSRI's have their own ADR's and are not the best.
You have done major investigations but do the suitability testing for HRT too - the current guidelines recommend usage in those needing it the most like your mother.
Check out this before proceeding any further.