The Serology 7 tests are useful tool in working toward a diagnosis, but are by no means conclusive. Likewise, many patients have high C-reactive protein and ESR during flares of IBD, but in the occasional patient these indicators of inflammation are not particularly useful because the patient can be quite ill without these parameters being much elevated.
When disease activity is restricted to the large intestine, it can be very difficult to tell the difference between ulcerative colitis and Crohn's and there is always the possibility that the diagnosis may one day change. It might be useful to think of yourself as having IBD rather than agonizing too much about which type of IBD it is. Generally speaking, most of the treatments are the same, with the exception of surgery (a curative option for UC but not Crohn's) and enteral nutrition (an effective primary treatment for Crohn's but not for UC). I realize that the uncertainty is frustrating, but remember whichever you have, it's a done deal, you can't change the fact that you have it . Your symptoms are your symptoms, whatever the name the doctor puts on them, so it can help to focus on setting up a plan to deal with the symptoms rather than worrying too much about the specifics of the diagnosis. Just a thought.