I'm not a medical professional, and I don't know your personal situation, but from personal experience, I can offer this advice.

If you have two small salads every day, or one small salad at one meal and one fist-sized serving of a low carb vegetable at another, together with your proteins, you should have sufficient fiber to feed your gut bacteria.

Be careful about using psyllium. Sure, it provides fiber, but that's all it provides. It doesn't have any micronutrients that you body needs. Also, be careful about how much psyllium you eat at a given meal. Be sure to drink a full glass of water whenever you use psyllium because if you don't, it will make you constipated, and no one wants that.