Ovulate on day 14/28 day cycle. My endometrium is 6mm on day 19 of cycle. Any chance of pregnancy?

Yes. The data on the thickness of the lining is based on the thickness and appearance of the lining during fertility treatment cycles at the time of ovulation. The lining will thin post ovulation to some degree. If you were not on fertility drugs and not at the time of ovulation the lining measurement may not mean much. You have to wait and see :).