I have worked as a women's health physio, so I can offer some advice from a professional, rather than personal, point of view. This isn't a problem most physios would deal with themselves, but of course we are trained to recognise and understand all sorts of other problems so that we can refer on appropriately as well.
What you're describing is frequently caused by the bladder overfilling post c/s, and damaging the nerves, as you've been told. At this stage of things, it is not going to simply get betteer on its own. I would suggest you go and see your Gp and let him/her know that you'd like to have it thoroughly investigated by a specialist who deals with female urinary problems (usually a gynae.) The gynae will ask you a million questions, possible get you to fill in a 'bladder chart' for a few days prior to the appointment where you measure and record how much you drink and pee, and when, do various tests to determine exactly what is causing the problem, and recommend a type of management. It isn't always curable, but it can sometimes be helped to different degrees. More importantly, chronic urinary retention can lead to other problems such as infections in the bladder and kidneys. When the urge to urinate is absent there can be a tendancy not to empty the bladder fully, and you will need to learn some techniques to make sure your bladder always empties completely.
I completley agree with Marydean - get a referral to an incontience nurse. They are fabulous at sorting these issues out (speaking from experience here).
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