NCOT, I was in same position as you when I was 20 yo and that was 20 years ago and had been in hospital for 5 weeks when they said you can either have an ileo or go home on pred and think about
it. I bolter for the hills, the thought of having a bag at that age scared the living daylights out of me and I believed I would cope with the pain and lack of real life. Well within a week I was on the phone begging the stoma nurse to get me in for the surgery. She got me in within 3 days and as soon as I woke up from the surgery I wasn't in any pain from the CD and wasn't running hell for leather to the bathroom.
It wasn't until a good 6 months later when I had put on 3 stone in weight, eating anything I wanted and living my life to the full that I knew how ill I had actually been without really realizing it. Even though I also had small bowel disease and have had flare ups of this since I had never had the pain I had with the colon.
It is a very personal discission and one only you can make. All I can tell you is that despite having further surgery from CD as mine is still in small bowel and will always take the azathioprine I have never once regretted having the ileo done. I gave me my life back and allowed me to live it to the full and I have never looked back.