I know the cause of my problem

Nearly everyone with IBS has their worst bowel problems in the morning. While this can be linked to anxiety and stress, the most common cause is your body gets woken up from being asleep all night and everything gets cranked up. Most people (IBSers and normal people) have a bowel movement in the morning. This is just becuase your intestines have been slowly processing food all night long, and when you get up, that cues them to evacuate.

There's not much you can do to avoid the morning bathroom rush. A few things that people do to help is to get up earlier, so they can have their problems and get over them and still have time to get to work, and not eating breakfast first thing. I eat my breakfast when I get to work (sometimes an hour or more after I get to work). I started eating it at about 9:15 this morning. I woke up a few minutes before 7. I got up, worked with our horse, came in and took a shower, had my morning poop, got dressed, drove an hour into work, got settled at my desk and only then started in on breakfast. If my guts are acting up a little bit (or I'm not very hungry), I might wait to eat breakfast until 10 or even 11, or skip it all together and go straight into lunch at 12. I find the longer I wait to eat after waking up, the less likely adding food to my GI tract is to upset me. The first meal of the day is always more of a loose cannon for me than the last meal. If I have to, I skip breakfast, then have lunch, dinner, and then some form of post-dinner breakfast. Same three squares a day, just running on a later schedule.

Stress and anxiety do not CAUSE IBS.  If your doctor is telling you that, he is giving you erroneous information.

While the exact CAUSE is not known, it is generally believed that an IBS gut has a heightened sensitivity to the normal function of bowel contractions as well as nervous system complications.  Like you, IBS CAUSES my anxiety, not the other way around.  However, after living with this condition for over 30 years, I suspect that the two are so closely interwoven that I almost can't separate them anymore.  Simply living with a heightened awareness of gut volatility would cause anyone to experience anxiety.

Morning can be stressful for everyone with IBS.  For me, it sets the tone for the day.  If I have a bad morning, either way (C or D), I can predict how I am going to feel physically for the next 12 hours.  Unfortunately, this awareness can become a preoccupation that can limit how one functions in the world.  If I know I am going to be in pain and distress for hours, or I fear I may have violent D, I am not going to feel inclined to participate in regular activities.  That causes stress, especially if those regular activites include work or child care, etc.