I need some advice

Sooooo my periods have been quite irregular this year. My last period was on the 16th of August and lasted a week. I wouldn’t even say it was a period tbh it was very very light. No cramping either. But on the 23rd of august(last day of my “period”) I had sex. And I still haven’t got my next period! 😬I took a test about 3 weeks ago and it was negative. Should I test again? Surely the test would’ve come back positive if it was that long right? 😳 on a side note though, with my first baby, I swear it was over a month from the time I BD to when I got my positive test. I don’t know how that happened but it’s crazy. I’m just thinking maybe this is the same situation?😳 what should I do?