A bit off topic, but I would be curious to hear about the process in which your doctor(s) diagnosed your cancer. Mostly because I would not think to attribute fatigue as a common symptom of cancer.
However, I didn't have those symptoms until the cancer was Stage 3, and I was lucky it was rectal. If it was up further in my bowel, obvious symptoms may have appeared too late (and I'm 36, so too young to be considered for regular colonoscopies).
However, it should be noted that fatigue is a common side effect of many cancers, and shouldn't be ignored if you've been fatigued for a while.