Late but all BFN😢

Cindy
Hi everyone! My last AF was August 12. I have 40-45 day irregular cycles but my 2 last ones were pretty regular about 40 each( AF arrived as predicted with Glow). I had unprotected sex on septmwber 15 and after 7 days I had cramps both sides and in the lower center of my adominal area, I felt something that I have never felt before And hard to explain and then some light cramps like when AF is going to arrive but she didn't. I have pregnancy symptoms like sore and tender boobs, tiredness, backache, light nausea that comes and goes but so far all of my HPT have been negative. Any thoughts on this? Or has anyone have experience something like this? Thank you!