normal menstrual cycle duration - #7204

I’ve always heard that a “normal” period should come every month, but when I actually started tracking my cycle, I realized that mine doesn’t always follow a strict 28-day pattern. This made me wonder—what is the normal menstrual cycle duration, and how much variation is considered normal? From what I read, the normal menstrual cycle duration is supposed to be anywhere between 21 to 35 days. But does that mean a cycle length can change every month, or should it be roughly the same each time? For example, if one cycle is 26 days and the next is 32 days, is that still within the normal range? I also noticed that my period length itself varies. Some months, I bleed for only 3 days, while other times, it lasts for a full week. Is it normal for the length of the bleeding phase to change, or should it always be consistent? What factors can make periods shorter or longer within the normal menstrual cycle duration? Another thing I’ve been wondering about is how lifestyle factors affect the normal menstrual cycle duration. Does stress, weight changes, or diet impact how long a cycle lasts? I’ve heard that excessive exercise can make periods irregular—how much exercise is considered too much? I also saw that birth control can affect the normal menstrual cycle duration. If someone is on hormonal contraception, does that mean their cycle isn’t "real," or is it still considered normal? And what happens when they stop taking birth control—how long does it take for the cycle to regulate? One of my biggest concerns is whether irregular cycles are a sign of a medical problem. If someone’s cycle is consistently shorter than 21 days or longer than 35 days, does that always mean there’s an issue like PCOS or thyroid problems? What kind of tests should be done to check if there’s an underlying cause? For those who track their cycles, have you noticed a lot of variation in your normal menstrual cycle duration, or is it always the same? Did you find any lifestyle changes or medical treatments that helped regulate it? I just want to understand what’s truly normal and when to be concerned.