Dear Doctor, I hate using public toilets, hence I tend to hold my bowl to find a convenient toilet. By the time the urge disappears. Is it bad? How?

Not a big deal. It's always better to empty your bladder when you feel full. However you are unlikely to do damage by "holding it" on occasion until the urge eases. Try to anticipate availability of a "convenient toilet" when consuming liquids, but don't lose sleep over this one....