@Chloe do you mind me asking how often sex took place in the fertile window?
I didn't know I was within my ovulation window at the time as I hadn't started testing. It was the week after our wedding on our honeymoon, so it was every day for about 6 days. I thought I'd caught later, but at my 12-week scan, it dated back to the week of our honeymoon.
I got pregnant in the first week of trying, and I have PCOS, so I would say it is definitely possible!