Does overweight rule out the possibility of celiac?

Hello doctor,

I have a concern about my cholesterol levels and the possibility of an underlying condition. I am a 37-year-old female with uncharacteristically low cholesterol. I donate blood regularly, which gives me the opportunity to have my total cholesterol level tested. About a year ago, I created an online account with my area's local blood bank, where I found they keep a record of your past health screenings. It was at that time that I realized how low my cholesterol was. The lowest being 118 mg/dL, which was several years ago when I was in my 20s.

But, most recently and over the past year, my levels have averaged in the 134-137 mg/dL range. For my age, I have been overweight for close to 10 years. I had never been on a diet or limited my cholesterol intake. I began researching online for any information that might explain levels this low. While there is an abundance of information regarding high cholesterol regarding its causes and risks, there is practically no information available regarding low cholesterol levels or causes outside of the obvious low cholesterol intake (vegetarian or vegan diet) or use of cholesterol-reducing medications such as statins.

With one exception: celiac disease. As I began to read through the signs and symptoms of this disease, I could not believe how many I had been experiencing. In fact, some of these were things I never even realized were symptoms of anything. One specific symptom, however, that each and every article I read seemed to use to define celiac disease was weight loss or being severely underweight.

Months later, I stumbled across an article about celiac disease going undiagnosed because of the misconception that with celiac disease you cannot be overweight. So, I decided to raise the question with my GP. Unfortunately, after giving the doctor a rundown of my symptoms and explaining my concerns, as soon as the word "celiac disease" came out of my mouth, he quickly dismissed this as a possibility, stressing that because I am not underweight, it was absolutely out of the question that I could have the condition.

He then dismissed all of my symptoms, saying they were nothing to worry about, and added that the lower my cholesterol was, the better. In his words, I should be thrilled at how low my cholesterol was, and I must have good genes, and with that, he sent me on my way. For close to a year after that appointment, I too dismissed all of these symptoms. Then, six months back, I was admitted into the hospital for an emergency cholecystectomy due to gallstones that caused me to have a severe gallbladder attack.

At the time, I knew nothing about the gallbladder's function or its purpose, so there was no argument from me when the doctor explained that some people just get gallstones and the only way to treat gallbladder disease is to remove the gallbladder. Needless to say, in my week at home following my surgery, I spent a lot of time learning about the gallbladder, and almost immediately I found information describing the correlation between gallstones, gallbladder disease, low cholesterol, and yes, celiac disease.

This past weekend I attempted to donate blood, and for the first time in my life, I was turned away because my iron was too low. I went online thinking my iron counts for previous donations would be noted in my wellness chart, although they were not. My cholesterol result from my previous donation, just 2-3 weeks after my surgery, was down to 128 mg/dL.

1. Would the fact that I am overweight truly rule out any possibility of celiac disease?
2. If it would, what other conditions might explain all of my symptoms?
3. Are there any other conditions with the same or similar symptoms that are also present with weight loss or being underweight?
4. If celiac disease should be ruled out due to being overweight, what can I do to convince a doctor to test me for it?

Kindly advise.