What Causes Two Periods With Short Intervals When Having Regestrone?

hello doctor,My age is 24,height 5.2 and weight 59kgs..I got married on nov 7th 2010..Till my marriage my periods was regular.After marriage till jun 23rd 2010 it was regular , then i dint get periods for the month of july.I used strip test to check my pregnancy ,but it was negative..And then i got my periods on Aug 9th and it continued till Aug 19th.I was taking Regestrone tablet under doctor guidance.I completed it for an week(21 tablets).date of completion of that tablet was Aug 30th,,After 2 days i got my periods again and its heavy too.Doctor advised me to take Ovral G now..please let me know whether there is any complications in this.can i get pregnant?