HI! You sound just like me a few months ago! It's such a hard thing to deal with it, isn't it? I am sorry you are even having to go through this. THat being said, this is what happened to me.
When I was 21 (1999) i first got sick, and two years later was diagnosed with UC, I ended up in the hospital 4 times, had to take steroids so many times i couldn't even count ganined all kinds of weight from them, then I got pregnant, in 2004 and i was great while i was pregnant, and I after i had my little boy (june 2005) i got worse again, I stayed sick for over a year, and in August 2006 i went to my GI and I said, "Can you just take the whole thing out?" He said, that would be an option but that he wanted me to try remicade, and I really didn't want to, but I did it anyway. And at first it worked great, but only for a few months, and even while it was working, i was still nervous that at any time it would quit working. And when it did stop working it made me wish i had never taken it, because i had wasted more of my life on something else that didn't work. So in Feb 2007 i went back and I said, I want it out! My GI tried to get me to take all these other things and blah blah blah, and I said, no. I acutally told him, "Either you find me a surgreon or I will do it myself!" He wasn't too pleased with me, lol. So he set me up with an appt and my GI kept trying to push the J-pouch but I did research and I decided against it. So on April 17, 2007 I had the surgery and had my colon removed, and i have a bag now. And it has been great! I actually felt better (even though I felt icky from the surgery) overall than I had in years within a week. It was amazing.
I was like you though, I was terrified, what if I wake up from sugery and they have a cure? And my Mom told me the same thing your frineds and family told you, lol. I have been swimming since and I have been fine. I am 30, so I am a little older than you, but I honestly wish that I had had the surgery when I was 21 and not wasted so much of my life!
As for the clothes, the bag shouldn't keep you from wearing anything, but for the first couple of months your tummy will be tender, and kind of swollen, so tight clothes might be out for a while, but all that should go away. My stomach was tender for abotu 3 motnhs, and still is at times, and most of my swelling has gone down, I don't know that mine is going to go away, i have had a baby and all though, so that makes it harder.
I am so much happier now though! I have a job again, I can take my son places, I can eat whatever I want, no more meds!