College was when it got to be a prob for me.
Instead of going in my suite I'd seek out more private locations on campus.
Like many others, there's been a gradual worsening of the condition- fewer 'safe' places. This is from allowing unhelpful, destructive thoughts to dominate, 'proving' that it's not ok to go in public, etc.
i'm sure there's something to be learned from the origin of our issues with public defecating. Mostly it's the same story - some experience in childhood which, over time, led to incorrect beliefs about the need for privacy. Steven Soifers book, while it's about shy bladder and not shy bowel, goes thru a number of likely explanations.
In terms of improving the condition, understanding the past only goes so far, even if you truly see the errors in your childhood reasoning.
I believe what you need to do is train yourselves to fill your head with recollections of 'successes'.
We currently, consciously or not, reinforce parcopresis by worrying. Pick out some past experience, no matter how old, where you did go despite not having ideal privacy. Be aware of your thought, and every time you notice you're worrying, redirect your thoughts to a vivid recollection of the successful experience.
Behavior and beliefs are influenced by the content of your thoughts. You need to make it so that the majority of thoughts on this subject are positive. Not just 'logic' like 'i can, everyone does it' etc. But remembering successes, and redirecting your mind to them every time it goes toward the worrying.
Anyway, besides the suggestions Baz makes on