4/5 days late

Jasmine

So my fertile days where the 4th-10th my ovulation day was the 8th I had sex on the 1st, 4th, 8th and the 9th and my periods now 4 days late. I took two pregnancy test and they both came out negative I’m wondering am I pregnant or could my cycle just be changing? I don’t have any symptoms except occasional nausea and diarrhea which I’m not really sure diarrhea is associated with pregnancy can someone help me?