I saw your post today and I just had to reply because I sooooo know what you are going through. To answer your question, yes some people are really sensitive! I am definitely one of those people. It took me a long time to figure out what I can and cannot tolerate. Mostly I've figured things out by trial and error (unfortunately). It is really hard because there are so many "gluten free" products on the market now that look really delicious, but I cannot tolerate 99% of them I have not found a brand of potato chip that I can tolerate, and I'm pretty sure I've tried them all. I make my own in the oven now. I also have not found a brand of cereal that I can eat. I make hot cereal from brown rice that I grind in a coffee grinder though. I had really made peace with it for the most part, but now that I am pregnant I can't even walk down the cereal aisle at the market without wanting to cry. Anyhow, I know everyone is different in what they can and can't tolerate, and I know that some people are even more sensitive than I am. But below is a list of processed foods that I have found I can tolerate so maybe this will help you.
Tinkyada rice pasta
Silk Almond Milk
Kraft BBQ Sauce
Smuckers natural peanut butter
Kinnikinnick white sandwich bread
Hunt's canned tomatoes
I am usually ok with the regular store brand of granulated sugar or brown sugar although I have used Domino with no problem too. Also, never had a problem with any brand of olive oil I've tried. You can make amazing peanut butter cookies from just peanut butter, eggs and sugar (if you can tolerate these foods).
Hang in there, it will get easier!