Part of me wants to hear her say you are completely fine. How much better would I feel hearing that! That would change my life.
Lindsay, I'm going to disagree with the rest of the posters here and argue that canceling your test is INDEED the right thing to do.
Listen. This is the nature of health anxiety. We believe, that because we experience PHYSICAL symptoms, that we need PHYSICAL tests and confirmation of PHYSICAL well-being in order to feel less anxious. However, this is categorically untrue. You could very well feel a sense of relief when the doctor tells you you're all clear, but two things will inevitably happen (as is the case with every HA sufferer ever). You'll either continue to have wonky BMs and start to fear that they "missed something." Or, if this test does quell your colon cancer fears, then I almost guarantee that you'll being to fear some other disease.
Medical testing or any other kind of reassurance is never the key to getting over HA. It never has been and never will be. HA is a mental disorder and therefore needs proper mental health care. Your instinct to seek out therapy and possible medication are correct. Those are slower, more holistic options, but they're REAL solutions to your problem of HA. Seeking out that kind of treatment will provide MORE of a guarantee that your family will have the present mother and wife they need.
You're 26. Your chances of having anything remotely sinister in your bowels is slim to none. Perhaps refraining from this test seems like a bad idea, and yes you'll still have cancer fears, but choosing to address and deal with the root causes of your anxiety will take you SO MUCH further down the road to real healing than any scope up your rear end ever will. I promise you that.