I have IBS. It's NOT psychological. Good God. Yes, it's often triggered by stress, but stress is physical. And I have it when I'm not stressed as well. It really bugs me when people act like it's all in your head. It's an intolerance to certain foods. I CANNOT drink coffee, ever. It's like an allergy. I often forget how bad it makes me and drink it, and get stomach pains and diarrhea right away. It's a lot of foods though, too many to just cut out.
I don't see how it ruins your life though - it isn't THAT bad, for me anyway, I think there are a lot worse conditions. I do agree that if you're stressing about it ruining your life, you aren't helping it any. Try to be calm about it. If you notice that particular foods irritate your bowels, cut them out for the time being. I find that eating lots of bran helps a LOT, just a bowl of bran flakes once or twice a day makes my bowel movements normal or close to normal most of the time. It's better to avoid doughy stuff like white bread and pizza, too. Eating brown bread makes a difference, and brown rice.
I find it comes and goes - I had it really bad a while back where I couldn't eat in a restaurant without crippling stomach pains, but it passed. When I notice it starting to get worse again, I try to eat loads of bran and a healthy diet, and it usually sorts itself out. It's a matter of trial and error, really.