I am exactly like this. I have to get up 2 hours and 15 minutes early when I am working, so I have plenty of time to poo, before going to work. Because I know I will not be able to go at work. Sometimes my stomach will be killing me, but I just have to suffer until it passes. I usually just take a simple sandwich for lunch, because I don't want to eat anything that may upset my stomach. I work 12 hour days, so that is a long time to hold it. Everybody always wonders why I won't ever eat out with the rest of them. The silly thing is I notice that other people poo at work, it doesn't seem to bother them. It makes me so mad! So yes I know how you feel...
Best of luck! Kelli