Hi Don
I can empathize with you. I have diabetes, neuropathy and sporadic incontinence. My Drs. think that the nerves around my bladder are shot, but I sometimes still get a sensation that I need to go. But there are times that I get no warning at all. In fact, I don't even feel it coming out, I feel the wetness on my leg as it comes running down or I'll feel the wetness when I stand up. I too have bowel incontinence which is very similar to your description. Just the other day, I had to go while walking into the grocery store while not wearing a diaper. The urge was so sudden that I didn't make it to the store restroom and had to drive home to get cleaned up.
The problem I have is the Drs. accept the answer that I am incontinent because of diabetes, but I can't get anyone to do a test that might explain why I sometimes know I need to go and sometimes I don't. I usually have no clue that my bladder is full. Sometimes when I go, a little comes out and sometimes I'm afraid the sewer will not hold it all.

It is hard to describe what the sensation that I feel that tells me to go but it does work sometimes for weeks or months. But my dry periods are getting less and less as I get older and I'm afraid at some point, I'll need to be in diapers all the time.
I'd like to know what state my nerves are in so I'm approved to see my neurologist to see if there is anything to get more understanding. Apparently Stanford has some program for doing these tests. I'm hoping I can get some answers, although not sure it will lead to anything. Nerve damage of this type apparently is hard to test and even if they find something, they can't fix it. I think that is why my urologist feels it is not worthwhile testing. That may be some of what you are getting too. What point testing because there isn't much that can be done it fix it anyway.