Hi..i Had Got My Periods On 18 July 2016...my Cycle

hi..i had got my periods on 18 july 2016...my cycle is 40-45 days.we are trying for a baby..On August 27 done
usg and BHCG.. both result are negative..Again i checked HPT on 5th September that also negative..i had miscarriage on 31-march 2016...i had Tab duphastone 5 days from 4th September still i did not get periods..but i have the symtoms of periods..and lower abdomen pain....i dont know what to do...please help me... thank you