Hi Kay,
A few points. First, my understanding is that water loss/gain as well as excretions are magnified (larger amount) in people of a heavier weight. Thus, as was mentioned before, it's apples and oranges to say 10 lbs in 6 months for you and same for someone weighing 150 lbs. I agree with others that regardless, such a small percentage weight loss means nothing sinister.
If you were suffering from the illness you fear, there is no way you would have no other symptoms. I say "other" but I don't consider the weight thing an issue to begin with. You would no doubt have extreme, like never before exhaustion that no amount of sleep can fix. Also, I take it you are in your late 30's. Statistically, ~ 1-10,000 people your age get CC, and more men get it than women. Many who do get early CC have a certain condition that causes literally hundreds of polyps to develop in their colon. Don't worry, if that were your case, it would have been discovered long ago. There's no hiding from that genetic condition.
Bob