What Causes Irregular Periods?

My husband and I are both 30 and just starting to try for a baby. Right up until two months ago I had a perfect 28 day cycle and always got sore breasts about 1 weeks before my period. Suddenly my cycle has become irregular and my breasts have not been getting sore beforehand.I was told during a cervical cauterisation at the start of the year that there were a few cells of inflamation on my cervix which were removed and tested for endometriosis. The results were inconclusive. This experience has left me concerned that I will have problems conceiving. Should I be worried about the change in my cycle?