So, in order not to avoid nausea & vomiting I have to take 1 bite of food every 30 minutes. I mean I'm only on the mushy foods stage, but damn it takes 3 hours to eat half of a potato

I found when I was still healing my food had to be really wet. Maybe some gravy might help it go down better.

Since my surgery I have found that foods I loved in the past, Tuna and chicken, just don't agree with me anymore. If your looking for something non-sweet how bout refried Beans?

Yes, that is not uncommon and it gets better. However, you shouldn't be eating a potato, that is a waste of your precious little appetite. Replace that potato with cottage cheese or hummus or greek yogurt or some other protein. You need to focus on protein, not carbs. You will feel much better and it will get you in a habit that is going to last the rest of your life...protein first, then vegs, then carbs last.

Mashed potatoes where on my diet plan since the puree phase.

They're put on everyone's plan but your dr should have told you to avoid them if possible. My dr said it should be my last resort because potatoes have very little nutritional value.

I wasn't told to avoid potatoes during mushies. But once I progressed to the next stage they came back off the list.