What you describe is common. Uc is a terrible disease that make us housebound and feel isolated from our peers. It's harder because it's a young person's disease, so you're friends don't get it and you just want to be normal. Something many of us have felt, we can relate.
I'd be aggressive in your treatment. Remicade was the only uc medication to put my uc into remission (currently 1, normal, nonurgent bm a day), and I hope it does the same for you. I was steroid dependent at 20mgs before remicade and in a flare for a year.
If remicade doesn't work (it does work for roughly 60+ percent) then I'd get serious about
surgery. As your young, need to put uc behind you, and 3 years of no relief is too much. It's your call but that's my feeling.
Regarding uc anxiety, try and find your escape, something you can do to get your mind off uc. It could be a hobby like reading, music, meditation, yoga, something to escape and relax. We all need to forget and get our stress levels down.
Try and keep your hopes up, have a plan, and whether it's remicade or something else then you'll beat uc