Ulcerative Colitis, Crohn's, Diverticulitis, or something else?

[A85N]

(This is reposted and edited, since I'm unable to delete or edit my previous post and wanted to simplify it)

I’m 33 years old. I got pregnant and gave birth four months ago via C section and was given antibiotics at that time. I didn’t have a BM for three days after delivery, and when I finally did, it was the biggest and hardest poop of my life. It was way bigger than I would have thought possible to fit through my intestines, and tore me a bit coming out, reaggravating an anal fissure problem I've had in the past. Then after that I began to experience very loose stools (almost like diarrhea but not watery) 3-5 times per day, that came on very suddenly and urgently. This got really bad around a month and a half ago when I started noticing mucus and a bit of blood, or bloody mucus in my stool. I didn’t experience any pain with this, but it terrified me, and I started googling and self diagnosing ulcerative colitis or some kind of IBD. I thought maybe the antibiotics and hormonal change after giving birth had thrown off my intestinal balance, so I started taking probiotics. These scary symptoms lasted around a week (during that time I was going 3-8 times per day), then they went away and I had normal BMs for a couple weeks, then I had a little bit of a recurrence flare up for one day, and since then have had maybe two or three more times where I saw a tiny bit of mucous or blood. I’ve also noticed often when inspecting the poop that my food doesn’t seem very well digested (tomato skins, black specks from banana that looks like banana bread, pieces of lettuce, etc.). I’ve also noticed several times that there are a few little bright red specks in the poop, that almost look like bright red plastic and not even food, smaller than the size of a grain of salt. I can’t think of what this could be, as I’m journaling everything I eat. Currently my BMs are no longer diarrhea, but are still mushy and barely formed, often shiny or easily break into particles when flushing. So even though things have overall gotten much better and I’ve been only having two BMs per day like normal, I’m so scared the blood and mucous symptoms will come back or continue. A couple weeks ago I started noticing a very slight pain, more like a discomfort that comes and goes, on my left side abdomen, to the left of my belly button. When I push on it sometimes I feel a gurgle. Not sure if this means inflammation in my descending colon or if it’s just a pocket of gas. I’ve cut out almost all dairy besides yogurt and stopped taking my fiber supplements. I have a colonoscopy scheduled for next week, and I’m trying not to work myself up into a panic. Any ideas what this could be? I’m desperately hoping they’ll just say it’s IBS brought on from the changes after pregnancy, or even that it’s diverticulitis. I’m the most scared of Ulcerative Colitis or Crohn's and of course cancer is worst case scenario.