From what you have said, it really sounds like you've gotten into a vicious circle of anxiety regardless of whether you believe the nausea is caused by it or not. You must be dehydrated a lot of the time if that's all you're drinking in a day. Being dehydrated can cause a multitude of problems by itself, nausea included. I think you should definitely mention how little you are drinking to your doctor next time if you haven't done so already.