Is Folic Acid Given After Having Suffered Miscarriage?

Hi sir i am haimonti from kolkata . i am 29 years old married woman. Having no baby yet. i have suffered missed miscarriage last november 2013. then my dr gave me contraceptive for 3 months after that gave me folic acid for 6 months , still i am taking the medicine. I am always suffering irregular period. so this month i have missed my period for 13 days. we have our intercourse after passing the date but without precaution. i have checked my pregnancy test its negative. so what is going on to me.