Trying to Concieve

Been trying to Concieve since November of 2014. Was on Birth control from 2009-2012. Been off completely since 2012. Periods were very irregular on birth control, once I got off it came every 5th of the month. Started to have back problems back in 2014 mid year, went to therapy for some medications and period went irregular for a while. Haven't had it for the past two months, within these past two months been trying to Concieve every other week. Been experiencing some symptoms, took about four test says negative on all??? 
Not sure what to do, been taking prenatals.. :(