I agree with liv_long. Each BC pill has specific hormones in it to trigger your cycle. If you skip one or something, you throw it all off.
When I was a teenager my periods lasted 2 days, were really light, barely any cramps. I was normal and fine!
Here are some facts from a real medical doctor that frequents MedHelp:
-The average duration of a cycle is 28 days but any cycle length between 21 and 34 days is considered normal.
-The average duration of flow is 4 days but anything from 2 to 7 days is considered normal.
-A woman is most likely to get pregnant on the three days preceding or the day of ovulation.
When I was on birth control I always took my pill even through the days that my period started. That's what you are suppose to do. Don't stop taking your pill just because you want to start your period on a certain day. Birth control pills are hormonal, so if you stop taking and then start taking them, then you are confusing your body by adding hormones and then taking them away.
I doubt that your period problem is anything to worry about. If you were bleeding longer than normal, I would be a little more concerned. However, you just have a very light period that is probably due to the constant unbalance of hormones.
Also my period have been normal since i was 10... and i've been on birth control for 4 months now.... my period has never done this... and i'm not worried about being pregnant, i refuse to see thats whats the problem....
I always don't take my pill on the saturday so it will start on the sunday morning... i've always done that since i started.... what my period is doing now is new...
A lot of young women have unpredictable periods. If you are on birth control, then your period should be more predictable. For me, birth control made my periods unpredictable and light and last NINE days. Forgetting to take a pill and then continuing to take your pills may cause the abnormality in your menstruation cycle. Most young women do not know when they ovulate(ovulate is when your ovaries release an egg. Also a time when you are not on your period, typically). If you are really worried that you are pregnant, my advice is to take a pregnancy test 5 days before the day your next period should start. If it's positive, go to a clinic(if you cannot discuss these things with your parents) and discuss your options with the doctor on site there.