I hate to say it but bloodwork doesn't show too much in regard to your diagnosis. As far as I know, you can have perfectly normal blood work and still have UC. During a flare up, it is usually thought that your immune system ramps up to fight the "infection" and causes your WBC to rise, sed rate to increase and your CRP to possibly be positive. In many cases, such as my own, I never had any of these markers for inflammation.
I have had pretty conclusive biopsies that show UC. The thing is, my GI, who is very honest with me, said that the possibility Chron's has not been 100% eliminated until you have an upper endocopy, pill cam, IBD serology testing, and even then, they can't say with 100% accuracy whether the condition would spread if you had surgery.
My point is, these biopsies, although the most accurate information available, still can not tell you with 100% accuracy what is going on. Blood tests even less so.
I hope you continue to improve and achieve a long remission.
I have read that some STIs can cause proctitis. You can get checked during a pap.