When Can Periods Be Expected After Missing It Last Month?

hi doctor.i m rose 28 yrs of age,from australia.i missed my periods last month(was supposed to b on 22 aug)after 4 days i consultd a doc and got to know i was pregnant for the very first time.but after 2 days i had a miscarriage.my doctor said it happens vidout any reason.its been 1.5 years since i hav been married and trying to concieve.i want to ask what shud b my period date now(as i hav not got it till date)?why it took us so long?m taking folik acid daily