I can't tell from your note, did you have a recent colonoscopy or not? You said you got an order for a colonoscopy, but it doesn't sound like the GI doctor did one. If not, and if I were you, I would push for a colonoscopy. It's been 6 years since you had one (2011), so it's not like you had a clear colonoscopy recently unless I'm misunderstanding your post, and I know several people that have been diagnosed in their 40s with colon cancer...including myself.
I personally don't see the point in sigmoidoscopy. If someone is checking my colon, I want them to check all of it. I had mucous and blood and hemorrhoids early on. Even as my symptoms worsened over time, I never felt bad and my blood work all looked good even when I was at the point that I was passing a lot of blood. They did a colonoscopy thinking it was likely I had colitis, but found I had cancer.
I was very lucky, the cancer was caught early and I only needed surgery, no chemo or radiation.
Clearly, this is concerning to you and you won't be at rest until you have been thoroughly checked. It also doesn't seem like the GI person really checked much.
Get another opinion. Get a colonoscopy and get some peace of mind.
46 yrs old @ dx
Colonoscopy for bleeding 7/25/11
Dx colon cancer 7/25/11
Sigmoid colon surgery 8/31/11
T2/N0/M0 0/10 nodes
Husband and 5 children
NED 6 years and counting