My period has lasted 2 plus weeks why?

Hi,
Here is a good explanation of how birth control pills work; it is from the "Go Ask Alice" website at Columbia University:
"Birth control pills prevent pregnancy through several mechanisms, mainly by stopping ovulation. If no egg is released, there is nothing to be fertilized by sperm, and the woman cannot get pregnant. Most birth control pills contain synthetic forms of two female hormones: estrogen and progestin. These synthetic hormones stabilize a woman's natural hormone levels, and prevent estrogen from peaking mid-cycle. Without the estrogen bump, the pituitary gland does not release other hormones that normally cause the ovaries to release mature eggs. "
Regarding your question on the change the regularity of your menstrual cycle, here is what the Mayo Clinic says, "The pill prevents your body from making hormones involved in ovulation and menstruation. When you stop taking the pill, it can take some time for your body to return to normal production of these hormones."
The "pull out" method is not the most effective way to prevent getting pregnant. I suggest your partner use a condom and that you visit your doctor to discuss other birth control options that will not make you sick.

I am a little confused on how the birth control works. I decided to start a new pack of pills about a month ago but I couldn't take the last four active pills because they were making me sick. So then the next day I had my period for three days when I normally have it for 4 to 5 days. And I usually have a 28 day cycle when I am on the pill and when I am not on it. So its been 7 days past the normal 28 day cycle. Now I am going on 35 days since my last first day period. If you miss the last four days of the pills how far back should it push your period? Or should I be worried or just wait it out? We've been using the "pull out" method.

Hi,
Call your doctor right away. You can expect to have a physical exam including a pelvic exam, Pap smear, lab tests. Your doctor will ask you questions to determine the cause. There is a range of possible causes from a change in hormone levels to thickening of the lining of the uterus. I will not attempt to pinpoint the cause, that can only be done by a physician who can examine you and obtain your medical history.