Spotting is not unusual after taking I pill
and may sometimes last upto your next period.
If it continues beyond your next period ,then consult your doctor.
As far as your next period is concerned,it may come in time and many times a week earlier or a week earlier.It can be lighter or heavier.
If it is delayedby more than a week,get the pregnancy
Many times,subsequent menstrual period may also be irregular.