What Causes A Short Period After Taking 'loette'?

hi, i am using loette for 2 months from now. last month i got my period on 15th dec. this month i got something on 14th january but it was only slight bleeding for just 1day or 2.my menstrual cycle is of 28 days and it is for 5 days. but this time it was very short. i can' t understand anything. i have also taken an i-pill in this month. i am confused with the bleeding and understanding it as my period have started taking loette again from 14th jan. please help...