Dana,
Yes, I feel your frustration! I know how hard it is to switch to a GF diet and you're right - it takes time to get the hang of it.
Modified food starch is generally regarded by the FDA as GF. Here is an excerpt from a letter the FDA sent Ms. Marie Kawaguchi (Founder of the Celiac Association of Northern Utah) in 2003:
In regard to modified food starch, the FDA does not require manufacturers to name the source of the starch because the starch isolation process used in preparing modified food starch removes the protein (i.e., gluten) component. Thus, modified food starch is the common or usual name of the product regardless of source. Although we acknowledge the possibility that traces of protein might occasionally trigger an adverse reaction, and we acknowledge your concerns, we have not been able to document reported cases of food intolerance to the modified food starches commonly available for commercial use. Thus, irrespective of the source, modified food starch is not likely to be a problem for most gluten intolerant consumers. Therefore, in the absence of information showing that modified food starch will trigger adverse reactions, there is no basis at this time to require source declaration.
When the term “starch” is used alone it is considered the common or usual name for granules of starch made from corn; alternatively, the name “cornstarch” may be used. Starch from other sources must be named using a non-misleading term for the source of the starch such as “wheat starch” or “potato starch.”
The complete text of this letter can be found on the FDA's web site
HERE.
Most cheeses do not contain gluten and are safe for celiacs. One major exception would be blue cheese, which uses bread. We have a thread
here about dairy and cheese. Ice cream, also, can contain gluten, especially "soft serve" ice cream. Cheese that is already shredded may contain gluten because they dust the cheese to prevent clumping. Usually, they use potato starch, but always check the label to be sure.
For right now, the best method for confirming a diagnosis of CD is endoscopy of the intestines. This may be why your physician is hesitant to perform this procedure if your child is asyptomatic.
I hope that helps answer your questions somewhat.
Carol