Hi, I am 25yrs old,5 4 and 100lbs/46kg.I used to have a 28 day menstrual cycle ,but starting from January 2011,my cycle suddenly changed from 28 days to 35 days.Is it normal?Rather than the number of days cycle changed everything is as usual only.I will be having heavy flow in the first 3-4 days and then just spotting for 4-7 days and that s it.I haven t done any exercises or anything different.I would be much obliged if you could help me.