I think you need to take a water soluble fiber supplement like Metamucil that contains psyllium. It is a stool bulking agent.
Eating too much insoluble fiber will cause you have a loose --- not firm stool. Insoluble fiber is all fruits and veggies including greens in toss salads, nuts & seeds, the outside part of grains-- bran that is in alot of cereals. Also, the out side part of beans and peas.