Newly diagnosed and a bit confused

I'm very new to UC and I'm hoping you good folks who have been dealing with it longer than I have may have some insight.

I started having loose BMs and cramping about 8 months ago, and it has very slowly worsened over that time, with movements being more and more liquid. However, I've never had blood in my stool and rarely have I gone more than 4 or 5 times in a day.

Went to my GP after a few months, did some tests, got a GI referral, standard stuff. Had my first colonoscopy on Monday and was diagnosed with ulcerative pancolitis immediately after. I was still partly drugged when I talked to the doctor and don't really remember much of it, which may contribute to my confusion, but he wrote down the diagnosis for me and prescribed oral mesalazine.

I've been reading into UC and the big symptoms -- blood, fatigue, etc. -- don't seem to be what I've had. Obviously I'm not complaining, I'm just a bit confused. My experience has been annoying and unpleasant, but not debilitating by any means. Do I just have a mild case of it that has been flaring for a surprisingly long time? Or should I expect things to get worse and bloodier over time?

Thanks for helping a newbie out!