I eat very few vegetables and nuts and am primarily on /r/zerocarb.
My gut bacteria eat plenty of collagen and like almost everyone else on this sort of diet, I've seen a severe reduction in the bloat you are complaining about as well as gas, and occasional constipation and diarrhea.
read this
Fiber is not nearly as important as you have been told, and may only have benefit in a grain-based diet.