You could go to your own doctor who would no doubt do some test to rule out things like UTI,and i would say that when that came back clear then he would send you a hospital for more tests about your problem.
But a you said yourself plenty of people who are icontinent have been for all the tests that they can do,and still they cant find anything that iscausing it,but why do you need to go through all of that just to tell people that youwet yourself and need to wear diapers.
Just come out to those who are close to you and tell them that you have a urinary problem,and that you need to wear a diaper 24/7,if they all love you the way you say they do then they will accept hat you have a medical problem,and that you need to wr protection all the time.
That way you do not need to hide your diapers when you go visiting,or when you have visitors and you will also not need to keep your diaper changes secret,afr all there are people of all ages who are in need of diapers 24/7 so dont worry about it and enjoy your diapers.