Just guessing...
...I don't have a clue what may be happening with you, but I wonder...
Could it be that, for some reason or other, your body is relying on 'the stretch factor' to move your bowels?
That your intestines have to reach maximum stretch/distention before peristaltis (sp?), the squeezing of the muscles sets in?
Luckily, if that is so, you are getting regular action, but I wonder how long that method will serve you.
For my peace of mind, will you try something?
Will you moderate what and how much you eat, and when?
Will you find yourself a nice organic produce department, and eat some raw, and some lightly-cooked vegetables, at regular intervals?
And, will you 'sit upon the throne' about thirty minutes after each meal, for about ten minutes? Leaning forward, stretching your spine a little, may straighten that last curve in the colon that slows down the progress of the stool. Grunting and straining, of course, does us little good in the long run.
And it is the long run that you need to think of. What will be your bowel function in another ten years...or twenty. You want to 'train' yourself to moderation, for a while.
Do the eight glasses of water thing...beginning with one glass (and then two) of WARM water first thing each day...before you get out of bed, if possible. Cold water doesn't do it. In fact, cold drinks could be part of your problem.
You also don't want to 'train' yourself to 'laxative' foods, I think. Leave off the 'processed' foods for a while, please. Eat simply, and wholesomely, even if it seems boring. Get yourself the basics, moderately cooked, even if you have to eat the same meals every day.
Munch a little kelp with at least one meal per day. Sip warm/hot water, as though it were tea, on a regular schedule, and take a small spoonful of Udo's Choice oil at least once per day. (Great for the brain!)
Get the best unprocessed
Sea Salt your healthfood store has...and avoid all pre-salted and pre-sweetened foods, they just don't use the kind of salt and
Sugar you need.
Accustom yourself to tiny amounts of wholesome, natural sweeteners, too.
This is NOT an issue of embarrassment. You were just lucky to notice the 'difference' through those incidents.
This is a matter of self-training. (Tell your friends that you are 'in training' if any of them notice. They will think you are so smart. They may even copy you, and you'll have a buddy or two to encourage you. Don't tell them what you are 'in training' for...let them figure it out for themselves. The side benefits are many.)
Decades from now, you will see what you avoided...and you will be glad.
Read back pages at the Ask Humaworm forum as much as you can.
My best,
Fledgling