My period always comes on different days every month; it is either two days before the due date or the exact day. i don't know when am i ovulating. i had protected sex after getting my periods. are there any chances of me getting pregnant?

Use a condom: Or other birth control, until you're ready to get pregnant.

Ovulation: It may be mind boggling every month to catch ovulation. Unfortunately, the pattern you described doesn't allow you to know exactly when you ovulate each month. Therefore, i'd recommend that you do ovulation test that will help you find out when your ovulation is likely to occur.

Rythm not effective: If youre avoiding conception you need to use something effective such as the birthcontrol pill as well, a condoms. See your doctor or planned parenthood right away for important contraception.