according to your description there is possibility of hormonal
imbalance like irregular ripening of endometrium, your symptoms could also be because of that, but as you are having irregular cycles predicting the day of ovulation is difficult, so there is possibility for pregnancy
also if you are having history of intercourse around the that time,
you consult gynecologist once and undergo blood test
for pregnancy once, if comes negative get one ultrasound
done to see the status of endometrium depending on that your doctor can come to one conclusion regarding your problem and treatment can be taken accordingly.