how do i convince doctor ??

i passed my glucose test and my last A1c's were 4.9 and then 5.3. Every dr I see says the numbers are good and I'm not prediabetic. But I get sick feeling (fuzzy vison, dizzy, headache) when I eat natural or added sugar, starchy foods, and carbs. I cut them from my diet but I want to know what's causing it. Other than testing blood sugar I don't know what to do or how to get my dr to take the concern seriously. Any ideas at what to look at? I get the symptoms when I eat

potatoes

melons

banana

dates

baked goods

barely

rice

bread