I have never had a true fecal occult test. My GP did. Digital recital exam and then rubbed her finger on the occult card and that was negative but I don't think that's an accurate way to do it. I was upset when I saw the Gastro too because I was hoping she would do the simple anoscopy to look into side the rectum and see internal hems.
Hon, I mean this in the nicest way possible, but unless you truly think the doctor is not doing their job properly, unless you have extensive knowledge of medical practices yourself that allows you to make educated observations about the accuracy of certain tests, then your misgivings are most likely due to your anxiety than any basis in fact.
I am not saying medical professionals should never be questioned - quite the contrary - but unless you have real reason to believe they are not performing their duties correctly, trust that they know what they are doing.
If you really truly have misgivings about their practises that won't go away, change to another doctor or get a second opinion; but even if there are tests that are not performed, it still doesn't mean you have a terrible disease lurking undiscovered in the darkness.
Look into getting therapy for your HA. That is of the utmost importance right now.