What is wrong with me? why can't i conceive?

Just missed my period ..15 days late today and all off a sudden I start to bleed... I have been trying to conceive with no luck and it seems to me that every other slapper that lives near me opens her legs once and shes pregnant whether she wants it or not? I have been TTC for 8 months and constantly seem to be getting BFN after BFN although I was 15 days late I was still getting negatives..My next option is to give up and go back on the pill! Im sick of the f****n heartache!