I know exactly how you feel. I'm 18 and halfway through my freshman year of college. I experienced my first ibs symptoms the day I moved in. The next attack was after I spent the night at the home of a family I babysat for (needless to say that was beyond embarrassing).
It's now 6 months and several useless doctors visits later. The only thing I know is that my ibs is completely stress related. Any change in environment or routine or one week full of stressful assignments send me straight to the bathroom with nausea and diarrhea for days. Now I don't know if I'm actually stressed by situations or if it's just the fear of getting sick that causes my ibs to act up.
I feel like I can't do anything. I'm scared to go places and do anything fun because I think I'm going to get sick.
I, too, have tried some breathing exercises and meditation type things to keep me from getting sick- a mind over body (or in this case, stomach) type thing. I also tried working out in the morning, as exercise is supposed to relieve stress. These always worked for a short time, however as soon as I thought I was fine, I would get another attack.

Believe me when I say I understand what you're going through. It truly is a horrible way to live. I'm sorry this (very long) post hasn't offered you much hope. I just like to know that I'm not alone in this.
I am considering going on some sort of anti-anxiety medication. I have another doctors appointment next week and will ask about it. I'll let you know if I have any success.

Please e-mail me if you ever feel you need some type of support.
tvqueen156@yahoo.com
(I know it's a bit silly, but my other account has my name in it).