HI( well come to HCM.
For irregular period commonest cause is ovarian cyst
, can be ruled out by simple
test USG abdomen. Other causes could be hypothyroid and hormonal
YOu have to consult your doctor and get done reports as per his guidance.Chances
are less you being pregnant as you done sex both in relative safe period.
Still want to be sure can do urine for pregnancy test is very simple. Thanks