Bowel problem (TW/Graphic)

(Warning stool pic below)

Hi all, 

I'm in my twenties and except for autism and severe anxiety I am reasonably healthy. I think so anyway. My diet is less positive, consists of mostly bread and sweets which does seem to trigger my IBS. As does the anxiety. What maybe isn't helping is that I only drink coca cola and have only drank this for the last 3ish years and I'm worried it and my anxiety are causing my body harm.

I get a lot of mucus when I have a bowel movement, I'm also very constipated sometimes and when I do finally go there will normally be blood (bright red), mucus and of late it has been lighter, either more pale or clay coloured. I mostly feel OK though I do get stomach ache sometimes and often firm stomach, but I've always put this down to IBS and anxiety. 

But now I'm feeling it might be something more. My first thought is cancer, most likely my anxiety talking though as I am quite young still and otherwise reasonably healthy. But I am worried I might be dying from this!

I've got a pic below and if you've had this or know knowledge of what's causing it please do reply as it will be a big help and put my mind at ease.

I will see a doctor if it's really necessary but I get absolutely nightmarish anxiety and would probably pass out before I even get to the doctors!

Sorry for the graphic pic but I really could do with some input here. Thanks in advance.