
I had my first panic attack at the age of 3 and have managed it with various medications particularly since the 1980s.
Your anxiety may well be hormonally linked. Did U keep your ovaries at the time of surgery? Even if they were removed there may be enough 'stump' left behind to cause fluctuations.
R U able to up the amount of Venlafaxine ? Do have a word with a Pharmacist or your GP about taking a more instant anti-anxiety medication with the Venlafaxine.
Is there a dedicated menopause Nurse/GP at your surgery? There are also NHS and private menopause clinics - don't bother with a gynaecologist as they often don't know much more than some GPs seem to do

some find that keeping a mood/food/symptom diary of use to chart progress. Browse round. Make notes ;-).