What disturbs me most about your post is your statement that your GI doctor is so negative about your reaching remission. Is he some kind of genie who can look into a crystal ball and determine your future? While I agree with him about controlling your UP with just oral Pentasa (personally I never took that medication), I would give the rectal meds some time to work. My doctor was never a big advocate of oral steroids but prednisone was the only med that helped me achieve remission. However, after suffering with UP for twelve years, being on 6MP for seven of those years (not helping much), trying Remicade (failed after 3rd infusion) and then Humira (no change after three months) and becoming prednisone dependent for two years....I had to have the surgery. It actually saved my life. I was almost 64 yrs old at the time of my operation.
My GI never recommended VSL#3 but I have a friend with UC who is having wonderful results using it...give it a shot too!!!
The best of luck to you!!!