>>396722
Gluten is a problem only if you have celiac disease, but replacing white bread and noodles with something healthier is always good. Leafy and fiber rich foods is good advice.
>>396748
There are different types of fiber and the type matters. Biggest distinction is between soluble and insoluble fiber.
>>396721
You should try a fiber additive. Psyllium husk is the most recommended and works well in my own experience. It makes poops bigger but cleaner and also more regular which helps a lot. It has a bit of a weird taste but works well mixed in with yogurts. Oat is another very good source of fiber to fix your diet. Or any bran should work.