Hi Tim,
My name is Rob.. aka sociologygeek.. and im pretty well known on this board... if you search my name.. youll find my posts dealing with my issues. My case is somewhat similar to yours.. but also different. The main difference is.. when my issues surfaced, I was dry as a bone at night but had dribbles that snowballed into floods over the course of the year. It started in 2008... but before then i often had dribbles on my undies and episodes of sudden release where i started going before i had a chance to get my pants open.. and it went down my leg

Then in 2008 I finally decided to start wearing some sort of padding.. at this point it was just dribbles.. but then it got worse... i ended up wearing the diaper style products..partly for capacity, partly for the fact that no other product, regardless of lesser need for protection..just does NOT work with the male anatomy. You discovered this rather quickly with the pullups.. yeah, i first tried the guards..but found them uncomfortable and inconvienent..strap on undergarments..same thing.. Pullups were sligtly better.. only if i ignored the fact that the waistline goes well above my jeans and they tend to sag... not to mention the gaps.. i found very few pullups that were adequate enough to contain enough padding... because of the male anatomy..its possible to leak from multiple points.. and all may not be necessarily covered by a pullup.. if ya know what i mean.. long story short.. i ended up wearing tape on diapers 24/7 because like you i never knew an incident would strike. The oddest thing though was while i was having Niagra falls sometimes durnig the day.. at night not a peep..
But while i dont neccessarily have the same situation as you, i definetly relate to the need for answers. At first, my doc assumed it was OAB..and put me on detrol..nope.. not helping.. VeSICARE..even WORSE..caused a dangerous dizzy incident while driving. after that.. i wasnt at all enthused about meds.. talk of Interstim came up...at first.. i was willing to try it.. but later, when i found out about the side effects.. and how most likely id STILL be wearing diapers some of the time.. im like NOPE..
So, after running the gauntlent of pills, urology visits galore.. being told i might have to live with this.. thinking its neurological.. getting that checked out.. and finding NOTHING wrong there... at last a very sharp and astute urologist at U of M.. who i will be forever indebeted to.. suspected it wasnt the detrusor.. so much as it was the spincter. he said.. i didnt have a problem holding it in.. i had a problem letting go.. which made sense.. but still didnt explain the floods.. but im getting ahead of myself here.. he thought the problem was my not relaxing the sphincter enough.. and he thought one of my meds.. Catapres was the culprit.. and sure enough.. there was a change.. but, not totally dry.. and then i underwent his suggestion of pelvic relaxation therapy.. that was my magic bullet. Not only did they fix the not empying part.. but they explained that the floods were most liklely a result of me not emptying enough.. and holding it in and in.. and finally my muscles fatigued and let looose.. it made sense.. and i went thru the training regimen.. and it worked.. im dry as a bone now.. and have been since 2010 or so.. so the moral of the story is dont give up.. investigate every angle..and if youre close enough to Michigan.. if all else fails.. give their Urology department a try.. i cant say enough about them..
Peace out!