I'm disagree with your doc about
enemas not helping.
My doc says that most of UC symptoms come from the rectal area even though the inflammation can be upward from there.
If you have bleeding you should be using enemas. And if that is so you should find new GI. No bleeding? Then it may be debatable, but it wouldn't hurt to try them for a few weeks and see if you have improvement in symptoms.
Juicing: I have juiced
and feel it is helpful. I use cabbage and carrots but not in large amounts. I used to make it in a blender using spring water to get it blended. Now I have a juicer and the juice is much more potent so less is needed. I don't add apple or fruit because sugar causes inflammation in me and that is what I'm trying to eradicate. Other people seem to tolerate fruit and juices better than I do but I can tell that sugar hurts because I feel aches in body parts.
Cabbage juice is known to heal ulcers. The question is how far it can get in our guts to do it before being digested. Try it and see if it helps. Fresh cabbage juice is not bad at all. You can add some ginger also but just a little. Wow ginger is spicy.
I am on the SCDiet which really put me into remission but if you just removed sugar (in all forms) from your diet you would be doing a lot to help yourself. Getting the inflammation down is key, along with stopping bleeding.
Some people (and most doctors) don't think diet has any effect. It's your life-you decide whether to try diet modification or not.