My period is usually a normal 28 day cycle, however the last day of my last period from January was January.29. According to my <a href="https://play.google.com/store/apps/details?id=com.glow.android">glow app</a>, it says that I should get my next period for this month on February.15 (but it's not 28 days; it's less. Does this mean my period will come the following week instead? Need some input please.