Hi Anna and welcome! Our symptoms are very similar. I also deal with mucus, which I can pass apart from a BM. Also, I don't have an issue with D, but my stools are very loose and thin/flat as you described.
Being that a CT scan has noted inflammation in your sigmoid & TI, it does sound like it could be Crohn's. Have you had a colonoscopy yet? In my opinion, it is the best way to see what is truly going on in there. Also, biopsies can be taken and tested for IBD.