I've always been hesitant to try any fiber agents - just really worrisome regarding causing any blockages, etc. I have been prone, mostly, to low motility, which causes a sort of constipation (and then SIBO). I have been handling that well. What would (either) fiber do? And, what is the difference?
This makes total sense! You know your body. After all, you live in it, and if it doesn't feel right, that's probably the best guide! From what I have read on the all-knowing internet (haha), soluble fiber (like psyllium) is more of a gut regulator than anything else. It can help with movement that is too fast OR too slow, but the slower you are, the more water you would want to take with it. I didn't take it for years because I thought it was only for constipation. It has helped my guts a lot, so I like to share that with people, but my guts, since takedown, have always had fast motility, and my bowel obstructions were from the guts flopping around and tying themselves in a knot around the adhesion where the ostomy used to be, not from stuff stuck in the intestine, so slowing down my too fast guts helped stop that from happening. (did anyone enjoy that endless, run-on sentence?) I hypothesize that, with lots of water, these fibers would speed up your too slow guts? Every once in a while I'll eat too much soluble fiber and my guts slow down too much because the output is too thick. My system is not accustomed to that at all! I just have to drink a bunch more water when that happens.
I don't know what to tell you about the difference between the effects of the different types of fiber. Flax meal has all those omega 3s and tastes more like food. And slippery elm seems a lot like psyllium, except it is harder to grow and less sustainable, so I don't use it much.
But all this is moot if your body is saying no to it. The body knows a lot and the intellect keeps us from listening.