Help!

Hello, so this is my first time posting but I really need help.

So I had unprotected sex in October on the 26th with 3% chance of pregnancy (according to app) but then my period for October showed up on the 30th and over lapped to November ended the 3rd (my overlapping periods are normal) now we are on December 5th and still no period, according to app I’m 7 days late. I took 2 pregnancy test today and both came back negative. Could I have conceived in October even though I got my period? I do have symptoms of cramping, sore breast, fatigue but no more than usual. Thank you in advance!