BFP 5 days after conception?!?

Elicks
So I posted a day ago about my midwife telling me my uterus being felt 2 weeks smaller than what I expected based on my LMP. 
​So, thinking positively, if my baby was actually okay and actually had a two week difference and was growing healthily, then I know exactly when I got pregnant. It would have been 5 days before I missed my period. 
​We had sex on a Tuesday, I missed my period Friday, Sunday I took a test and a Positive came we up right way. 
​I told my husband when we had done it that Tuesday, I thought we'd be okay because my period was coming (I could feel my usual leg cramps) so there was no way I could get pregnant! We even joked after that if I wasn't pregnant before surely after us doing it that time I was going to be! 
​if the two week difference is actually correct then I must've ovulated way later than usual. I guess it is possible, despite me having a regular period every month. 
​So I wonder if any of you ladies have experienced getting a BFP within a week of conception, even before you missed your period?? Or how many of you ladies have regular periods and happen to ovulate late from time to time? I just wonder how common this is, if it is even common at all! 
 
​It would also make sense for me about ovulating late, because we were trying for 2 months and I wasn't getting pregnant and I would try to have so much sex on the days I was supposed to be fertile! If I have been ovulating late for a while then I wasn't having sex on the right days.