If you had 28-day cycles prior to conception, you could have ovulated on 18th or 19th of June in all probability. If the length of the cycle was a little longer, the ovulation date would similarly change, but at any time, it is 14 days prior to the due date of the next cycle. So, I think you have understood the strategy behind calculation of ovulation date. Late ovulation does happen occasionally when there is an episodic hormonal
disturbance, but is not the usual scene. Hope this helps.