Lauren,
Although we are all very different, many of us seem to have problems with gluten and dairy.
You could try a food journal, but that will take time.
I would suggest you try going gluten and dairy free for a few weeks and see if that improves any of your symptoms.
In my experience, diet modification and doing Paleo was very helpful.
The other things that comes to mind is adding certain supplements.
I see that you are already adding vitamin d, which is good since there is a correlation between low vitamin d3 and IBD. I would also suggest you add: slippery elm powder and l-glutamine as well.
If you are interested, there are things IMO that you can control, which will have a direct impact on your disease, the symptoms you experience and their severity.
I was able to control my UC into remission through various supplements, probiotics, diet modification, and LDN , low dose naltrexone.
For more info on the protocol which has put me into remission, please go to this link: https://www.healingwell.com/community/default.aspx?f=38&m=1666318 , and look at the 11th post.
I hope you feel better and let us know how we can help you.