To me that sounds like Crohn's more than UC. UC can definitely affect that area, but when it does, it's nearly always affecting the rest of the colon as well (UC almost always starts at the rectum and goes in from there). Yours sounds more like the patchy distribution characteristic of Crohn's.
There are several ways to help differentiate the two. You and your doctor can decide which tests to run: Do a colonoscopy and take biopsies of the affected area in your colon; have these biopsies checked for UC or Crohn's. Check the terminal ileum, either in the colonoscopy or with CT scans; if there's disease there, it's Crohn's. Check the rest of the small intestine, either with CT scans or the capsule endoscopy; again, if there's disease there, it's Crohn's. Do the Prometheus IBD blood tests, which are pretty accurate at distinguishing UC from Crohn's.