Can you still get pregnant if you have post pill amennorhea? how long can it last?

Probably not: The fact that you are not having periods is a sign that your ovaries are not functioning and therefore not ovulating. Because of that, you are not producing the essential female hormones, estrogen and progesterone. You may have a common ovulatory disorder called pcos, caused by the ovary not processing the pituitary hormones correctly, leading to the lack of ovulation.

Eventually probably: Post pill amenorrhea is the failure to resume normal cycles after stopping the birth control pill. It can last for up to 6 months. During that time conception cannot occur because of the lack of ovulation. Once ovulation resumes, then pregnancy is once again possible.

Yes: Usually it will only take about a month for your periods to reestablish themselves after you stop the pill. This occurs because at some point you begin ovulating again, so you are definitely at risk to become pregnant though it may be hard to know exactly when this is. If your periods don't resume within 3 months after you stop the pill you should be checked.