Pretty messed up question but DEFINITELY need an answer😶🤔😯

So this may sound weird but i really need an ANSWER.

You have a kind of regular 28-32 days cycle, which means that u probably ovulate around the same time each month. And, you have sex 8 days before your period is supposed to start, AND then your period come at the time that it was due..does it mean that conception did not occur? Or the egg got fertilized and its waiting for the uterine lining to be ready again ( for it to implant )? Or is it impossible?

I took a test like a week after my period ended and it was negative.

I dont understand much in these things cause i was so bad at biology&health; classes but i did some research and still dont know so i need an explanation..