The diet I'm following now suggests alot of boiled vegetables so it definitely narrows down the possibilities for me, but I'm thinking that I should eat the vegetables you mention, even if they are a bit starchy when boiled. My pain is not that bad after all, and soothing my stomach for a period in my life is not such a bad idea!
Interesting that you say that streaks of purple in your tested vegetables doesn't affect you, I thought every sign of reaction with iodine meant it would be bad for you. That would mean alot of the vegetables! Definitely going to remember that when the diet starts calling for raw vegetables