You are your best advocate. It is important for you to know your body best, learn as much about UC as possible, and the possible treatments and side effects.
When my daughter was first diagnosed and we learned all about UC and treatments, we swore she would never go on the more powerful drugs (6-mp, imuran, remicade, humira). Over 1-1/2 years she was either in remission or a full-blown flare. Each time another drug stopped working and prednisone was the only thing to get her into remission, we had to look at the next drug. By the middle of of her 2nd flare her doctor, who is very conservative with drugs, really thought 6-mp was the next drug to try. After being in an intense flare for almost 2 months, any drug was starting to look good if it helped her. It made it easier to accept a more powerful drug because we trust her GI and he started her out on the lowest dose he felt would work and tested her blood often. Unfortunately she flared again and remicade was tried. At the same time we decided to speak to a surgeon just to learn more. By then, Remicade wasn't helping and the flares were becoming more frequent and harder to get out of. She never wanted to start Humira.
She had her surgery while in remission. The best time to have it but also the most difficult time to make that decision. Why remove something that is finally working well again?!
One of the reasons she chose surgery was because of the damaging side effects the drugs could have. She is only 17. She would possibly be on these medications for another 50-70+ years. That was a big fear. For her, more than surgery. She hasn't regretted surgery.
It concerns me that the nurse is so pushy about you starting humira. I agree with others that maybe you should get another opinion. The final decision is still yours. You can say no to any treatment offered. It sounds like you need a doctor (and his office) who is more on the same page as you (move to the next drug if and only if you aren't responding to the drug you are currently on).