Seeing a Yellow Streak on Alternate Days of Haidh

Q: My haidh period starts from the 19th to 25th and the rest of the month passes in Isitihaza, but for the past few months its happening that during my haidh period there is almost no bleeding or very less, but my isithaza passes in full bleeding. Even this month it starts on the 22nd with only a yellow streak on alternate days, counting these days as my periods I am not performing Namaz. Is there a possibility that my habit might have changed? It has been a month and I am taking treatment as well. Hazrat should I stick to my current habit that is 19th to 25th even if there is no proper bleeding or has my habit changed?