I used to be a regular 5 day cycle. Easy to to spot and tell how my cycle would be(heavy, light,spotting) I'm TTC #2 and paying attention to my cycles I became more aware each cycle has been regular in timing but flow has gone to three days, obgyn is not worried about how long period is lasting as much as at least I am having one. Which was important.
always good to see a Dr if you need the reassurance. Every woman is different.