Prozac can cause motor issues. Movement disorders. So your twitching may
be due to it.
While this is complex... it does happen:
http://psychiatrictimes.com/p010533.html
It has to do with downregulation of dopamine over time, and low dopamine leads to restless legs, and other muscle events.

A comment on your list:
You can remove the potassium supplement. You are paying money for
very little. 99mg is a 'spit in the ocean' when one needs 3.5 grams to 5 grams a day! You can increase potassium intake with foods that are high in this mineral.

The Topamax can be problematic too. This drug depletes bicarbonate and creates a metabolic acidosis in the body. This can lead to all sorts of
symptoms. So does your doctor test serum bicarb for you?

If you eat something late at night, are the twitches better? A high carb food?
Try this and see. Many twitches can be low blood sugar induced. I read once up to 70% of muscle twitches are due to low sugar.