Diving while taking Prozac

[Subcooled]

My second question is about Nitrox. I am thinking of canceling my Nitrox dive because of risk of O2 toxicity.

You do not need to take the strongest possible blend. You could choose, on medical grounds, something that has a more modest excess of oxygen. You need to consult a hyperbaric doctor, or Divers Alert Network. I am not qualified to give you advice.

Is that a good idea? Or should I maybe just ask the instructor if we can do a shallow dive on Nitrox.

The key things to learn on a nitrox course are the Maximum Operating Depth and the risks of oxygen toxiciry (pulmonary and instant). Discuss with your instructor.