I understand your concerns about what if its crohns. And to me it definetly sounds like Crohns. UC does not go into your small bowel. and Crohns affects the entire bowel, every layer, where as you know UC only affects the first layer, or the mucosal layer, which wouldnt present itself as ulcers and such.
Your in a tough position and if I was you I would opt out of surgery until the last second atleast. You need to maybe even have another colonoscopy, or the pill capsule camera, and if you DO have inflammation or scarring or anything in your small bowel, then I hate to say it but you might want to go ahead with the surgery...because it wont get better. OR you can always just disconnect your colon...a lot of times when you take a diseased portion of bowel out of the fecal stream, it heals itself, which is what happened with my rectal stump....give it some thought, and as your surgeon about it if you've already got one, which I hope so since your talking about surgery, a GI isnt really a key factor in surgery, they just suggest, the surgeon will be the one making the "dr" decision about whether to have surgery, using the GI's notes and such but still....its up to the surgeon and you.
Hope it gets better for you. I know many times I was severely sick but still ended up not getting surgery, actually the first flare I had lasted constantly, I was bedridden and in the ER dozens of times within 3 months and admitted 4 times in about 2 and a half months, but didnt get surgery then, so make wise choices about WHEN and IF to get surgery please.