I'm sure you wouldn't want me for your nurse! Although I often think that non diabetic nurses have no real idea of the condition....you wouldn't want me bullying you, I'm quite sure!
I'd take things slowly, make small changes, measure what you're doing with your blood sugar meter as you go, and take notes. It might amaze you what some foods do to your blood sugar! It also helps to take notes, because you then have proof to show medical staff your improvement. It may be that this nurse is rushing you and trying to get your results to lower too quickly, these changes don't all happen in a day or even a week, sometimes. Rome wasn't built in a day!
The other advantage of low carb and very low carb diets is that they help to clear inflammation from the body, so it might be the way to go for your UC as well as your diabetes, since UC is also an inflammatory condition?
There are plenty of doctors who support low carb now, David Unwin, Richard Bernstein,Aseem Malhotra(cardiologist...interesting to see his views on cholesterol!)....loads, in fact, so find these people online and read what they have to say. From what you've said, it will be easy to baffle your nurse with the actual science, and have answers for her to shut her up.
Good luck, I'm sure you will get the hang of this and make a success of your own care.