Have you tried azathioprine? Some people that cannot tolerate the 6mp can tolerate this form of it better. Also - you are probably candidate for Humira. Since all other "regular" UC meds did not work for you, you should be able to get approval for off-label use of Humira. I would discuss with your GI.
Don't feel so bad about the 40mg not working. It's frustrating, yes, but 40mg has never put a dent in my symptoms.
Good luck with the IV steroids - and let us know what the surgeon says.