What Causes Delay In Periods When Trying To Conceive?

hi i have been diagnosed with pcod in moth of may 2010 and treated with metatime tablets for 3 months and diane35 for 6 month and decapeptile injections for 3 month and treatment is finished in november but during that period i was not with my husband and that time periods were regular and now i m with my hubby from last 3 month and trying to concieve this time periods not yet come it is 10 days late but pregnancy test is negetive wat to do help me out pls