If you have leaky gut, you will be sensitive to nearly everything you eat normally. What happens is little food particles escape through the leaks and your body's immune system starts to react to them. It sounds like that might be a possible explanation for what is going on with you. Maybe read up on that and work on healing your gut. You shouldn't be restricted to so few choices long term. Something is wrong and you've got to find out what it is so you can fix it.

You should be able to eat berries without huge gains. A one pound gain might not have been a gain at all, but just a water level fluctuation. Sometimes we chase phantoms. Maybe try the blackberries or blueberries again and see what happens. Strawberries can be problematic, so I wouldn't start with those.