For As Long As I Can Remember I’ve Had Mild

For as long as I can remember I’ve had mild digestive issues that have never been fully explained but never really caused a problem. I’m often gassy, bowel movements take a long time (especially in the wiping process) and there is occasional pain or discomfort, but it’s never been anything serious. I’ve been to doctors about this a couple times as a kid, and they always said I was fine or sent me home with short term constipation medicine, but that’s about it. For about the past year I’ve noticed a bit of bright red blood on the toilet paper after wiping. I’ve assumed this was hemorrhoids as the blood doesn’t usually appear until many wipes in, and there are often localized spots of mild pain and itching on the rectum. Nothing I can’t handle. Up until now I’ve assumed that the blood was due to hemorrhoids that were probably caused by IBS or something similar. But today I noticed a several bright red spots in the stool itself. It was also pretty dark (and slightly green) a few days ago-but not entirely. It was light brown for a stretch but then instantly turned to dark dark green, almost like striping on the back of a snake, within a single log. I’m still assuming and hoping it’s just IBS and Hemorrhoids, which we einly mild inconveniences that I can live with, but the Internet seems to suggest that colon cancer is also a possiblilty. Is there a way to rule that out?
I am 19, and slightly overweight, but other than that in perfect health last I checked (which to be fair has been a bit over a year now)