I agree if you've been on the pill a while, it can take time for your normal cycle to kick back in. I've known alot of women who had problems getting pregnant when the first got off the pill. We all try so hard to prevent pregnancy, it doesn't occur to us that the body wouldn't naturally revert back to doing its thing when you come off the pill.
However, UC can play a part in irregular periods or losing your period. If you're flaring badly, your iron levels are low and/or your bodyfat percentage drops too low, you can have problems. At my sickest, I had no periods at all for several months.
Diagnosed with ulcerative colitis spring 1999. Have been in remission for years with only a few minor blips.
Maintenance dose sulfasalazine. Probiotics, vitamin D, fiber supplement and fish oil caps. George's aloe vera juice and l-glutamine for gut healing. Mostly grain-free and dairy-free low carb diet.