I dunno
Missing AF could be for a few reasons...
Late OV, No OV, pregnancy, hormonal imbalance, etc.
What is making me think that maybe it isn't your cycle is that you had sex only once and it was a long time ago now.
If you think that spermies lives for ultimate maximum 5 days and that you should be able to test within 15 days, that means that even if you ovulated late that you should have your positive by 20 days after you bd'd.
I don't mean to be a poop and i really hope i'm wrong, but i remember you mentioning all those fun things that you have planned and i'd hate for you to miss out just because your period went missing