9. Days late 7+ BFN

Good morning ladies so according to the app I am late 9 days . I have taken over 7 pregnancy test all came out negative . The last 2 times I conceived I had a BFP within 2 weeks of conceiving and a week before missed period . It’s been just about 4 weeks since last had intercourse and now 9 days late . Is this a cycle change ? Stress related ?