Tangerine,
Yes, I certainly understand the gastrocolic reflex after eating. Just as with infants, following a meal our bodies have their own schedules may not wait for ours.

I have been surprised a few times. Normally the response would be a healthy thing.
I am surprised that your physician is not taking this more seriously. As you are soiling yourself despite your best efforts that would seem to justify his attention. Unfortunately, as few of us actually die from our incontinence, some doctors consider it to be of a lesser priority.
Do discuss enemas with your doctor to see whether they might be appropriate for you. A traditional bag enema, properly (I emphasize the word "properly") administered by your caregiver, should give you 24 hours free of concerns about a bowel accident. They are routine in the daily bowel management program of most with spinal cord injuries. Bag gravity-fed enema systems are inexpensive. Also, there are enema systems such as Coloplast's Peristeen that are designed specifically for those with SCI trauma and limited agility that can be administered either by them or by their caregivers. Unfortunately, these are a bit pricey unless covered by health insurance.
--John