What Causes Missed Periods With HPT Negative After Rupturing Ovarian Cysts?

Iam ttc since 21/2 years iam having irregular periods since 2 years due to pcos . I had laproscopy on 10 nov '10they ruptured small cysts on both ovaries and told i will get regular periods.it's due on 10 dec but till now i din't get my periods.pregnancy test is negative.some spotting was seen when i have intercourse.why i din't get my periods ?Is everything normal.