Thanks for posting your query at DoctorSpring.com
Let me address your queries stepwise -
1. Chances of her being pregnant are quite low. If one pill is missed, and then taken the next day, she still has full protection that oral contraceptives confer, that is more than 99 %. There was actually no need to take emergency contraception in addition to regular contraception, it offers no added benefit, and just adds to the side effects, the main one being unpredictable and irregular periods. What cycle day was she on by the way when this happened ?
2. Yes, her period could be unpredictable, because the emergency contraception was superimposed on the regular birth control, making the hormones erratic.
3. If she misses her period during this cycle of pills, then take a pregnancy test first of all. If it is negative, continue with the next pill pack irrespective of the missed period. You should anticipate a period that deviates from normal in terms of timing and flow pattern, but it would smoothen out over the next month. Just continue taking the pills , trying not to miss any more , and the erratic bleeding and spotting, if it should happen , will regulate itself.
Just remember, you DO NOT need emergency contraception, while on the pill, as long as more than 2 pills are not skipped.
All the best.
Please feel free to discuss further.