Anxiety about my digestive issues. Help!

Lots of TMI details about poop here.

Okay so I've always had bad anxiety and alternating constipation and diarrhea. My anxiety has been much worse in the past few months, and then a family member committed suicide a month ago and my stomach issues got much worse. I was having diarrhea that looked like there was chunks of food and things were not being digested well. Then I went back to having dark, hard pebble poops. So then I find out I'm PREGNANT. So then my poops went back to the diarrhea with lots of mucus and undigested food and sometimes a little red when I wiped, and then pebbles again. Then, I had to rush to the bathroom and I had a huge fart and this is so gross but very dark poop, almost black but not quite, came out. I'm really scared of having colon cancer or something. My doctor said anxiety can cause symptoms of IBS and my mom says it's all the anxiety and hormones. I'm somewhat of a hypochondriac. Please reassure me.