Chronic constipation. Of this problem?

I have been suffering from constipation for the past 2 months (feeling of not passing stool completely in the morning). Post that, the feeling sometimes last the entire day and I am even straining while passing stool. On and off I have been taking lactulose which gives some relief but not completely. I was taking lactulose twice a day but now I am taking it once every night. Currently trying to include enough fiber and water into the diet (trying to drink 3-3.5 litres of water). However, relief isn't permanent and I notice that certain kinds of food make my more constipated (white rice, chicken etc.) It's been an unhappy difficult situation. What do you advise I do and get rid of this problem? Should I try some Ayurvedic or other natural methods.