Concerned about incorrect diagnosis

Sorry if this is the wrong place for this.

I'm 44 and male and apart from the issues mentioned here I feel well. I was put on the rapid referral pathway a few weeks ago by my GP after he found a lump in my back passage. I'd had itchiness there for 18 months and occasionally blood on the toilet paper when I can feel it's been particularly irritated. Never saw it in the stool though. I think it was a collection of blood that had healed differently. The day after he examined it, it burst and I had bright red blood when I wiped which has stopped now. After an initial consultation with a clinician who didn't seem concerned I was referred for a sigmoidoscopy which found some small hemorrhoids and a small benign looking polyp which they removed, and an MRI which showed no areas of concern. Also had a FIT test which I've not heard about but I think was fine because on Wednesday I got taken off the pathway. 

I'm a bit concerned about being taken off it though. I saw on my notes from the sigmoidoscopy that the loose stool I've been having had been going on for less than six weeks. I think I must have miscommunicated this to the consultant because it's been going on for quite a while and I don't properly know when it started. Possibly a year or two ago. I don't think I recognised it as a problem until being in this process because although it was soft and occasionally thin, I otherwise felt well, was only going once or twice a day at most, wasn't experiencing any urgency to go, and it wasn't type 7 stool, so I attributed this to hemorrhoids making my stool come out strangely and food choices I was making.

When I had an initial appointment two weeks ago I'd been put on isphagula husk which at the time had made my stool look normal, but having finished my course of it my stool looks a little less well formed again and I'm worried that there's something in another part of the bowel that the sigmoidoscopy couldn't get to that's causing a problem. Now it could be because I've upped my fibre intake or it could be that without the isphagula husk in my system, a symptom of something more serious is no longer being obscured.

When I went for my sigmoidoscopy I was offered a follow-up colonoscopy because they found the benign looking polyp, and at the time I was overwhelmed and didn't know whether to agree to it or not. We agreed I'd discuss it with my consultant. I'm worried that if I agree to it now that I'm not on the referral pathway it'll take a while for it to come through. I'm also obviously scared of having a colonoscopy because of what they may find. I am trying to reassure myself that the tests they've done would have picked up any issues if there had been any, but I know they can't see everything. I'm going to try to contact the consultant on Tuesday to see what can be done. I've not had my follow-up appointment with him yet so I'm hoping that means I'm not yet discharged.

I had a little bit of relief the other day when I heard the MRI came back okay but I feel like I'm spiralling again like I was in the weeks after I first got put on the pathway because they've missed something and it's my fault because I didn't make my symptoms clear enough to them.